<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2021 Workiva-->
<!--r:81626668-e187-4023-9878-57d1dd12714f,g:bee2ebe9-1642-43fd-b391-9da3fa0e751a-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/Coverpage" xlink:type="simple" xlink:href="zi-20201231.xsd#Coverpage"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/Coverpage" xlink:type="extended" id="ibbf12dcb01d2463e9805d128cb334e1c_Coverpage">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_48c8f148-4162-4ed0-85c2-cdbd5cd752d7" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_DocumentType_48c8f148-4162-4ed0-85c2-cdbd5cd752d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentAnnualReport_004dd46d-c889-456b-96c5-ad30c01bd328" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentAnnualReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_DocumentAnnualReport_004dd46d-c889-456b-96c5-ad30c01bd328" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_cf56b0a4-847f-4f13-a125-f73baffaa73a" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_DocumentPeriodEndDate_cf56b0a4-847f-4f13-a125-f73baffaa73a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_22512952-66d3-49cf-8cce-4c00217e305b" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_CurrentFiscalYearEndDate_22512952-66d3-49cf-8cce-4c00217e305b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_c224243b-e20a-4008-8e67-59c0b40569d5" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_DocumentTransitionReport_c224243b-e20a-4008-8e67-59c0b40569d5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_fa15348a-485a-41fb-bfda-8c37c9b1a6d7" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityFileNumber_fa15348a-485a-41fb-bfda-8c37c9b1a6d7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_e81d244f-65b3-4077-90d8-2990744eab01" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityRegistrantName_e81d244f-65b3-4077-90d8-2990744eab01" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_13b3ede6-700d-4ce8-a0ce-2fe090b6ef73" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityIncorporationStateCountryCode_13b3ede6-700d-4ce8-a0ce-2fe090b6ef73" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_ce1bfc52-baa6-4bf0-b08a-840f5fd2fb86" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityTaxIdentificationNumber_ce1bfc52-baa6-4bf0-b08a-840f5fd2fb86" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_5bc51792-18dc-4d85-9271-673f4f74f450" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityAddressAddressLine1_5bc51792-18dc-4d85-9271-673f4f74f450" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine2_43bb9ac3-3fc8-4af0-954e-79cfd6a9f0cf" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressAddressLine2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityAddressAddressLine2_43bb9ac3-3fc8-4af0-954e-79cfd6a9f0cf" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_76ba0598-4a49-4f76-8514-3ec2fcf67b0b" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityAddressCityOrTown_76ba0598-4a49-4f76-8514-3ec2fcf67b0b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_ea3988e0-706f-4224-9da3-af1b3f61dd78" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityAddressStateOrProvince_ea3988e0-706f-4224-9da3-af1b3f61dd78" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_74f0a1ed-1933-4d0e-b2c2-b0a46a1375ab" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityAddressPostalZipCode_74f0a1ed-1933-4d0e-b2c2-b0a46a1375ab" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_e837e078-9015-4d88-aeff-7cd02cb61377" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_CityAreaCode_e837e078-9015-4d88-aeff-7cd02cb61377" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_57dfa2c9-9ec5-4a5f-b35a-f3e89496b8d4" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_LocalPhoneNumber_57dfa2c9-9ec5-4a5f-b35a-f3e89496b8d4" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_bbf9a577-aaf1-425d-8096-7b4c9e5d2388" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_Security12bTitle_bbf9a577-aaf1-425d-8096-7b4c9e5d2388" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_617f2748-d8ff-4918-9c8b-60465b37aa39" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_TradingSymbol_617f2748-d8ff-4918-9c8b-60465b37aa39" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_e8aa8f1c-b216-4827-ae61-a8ceba13412a" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_SecurityExchangeName_e8aa8f1c-b216-4827-ae61-a8ceba13412a" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityWellKnownSeasonedIssuer_e5b264d8-a6a0-4130-bc3b-21b6505063c1" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityWellKnownSeasonedIssuer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityWellKnownSeasonedIssuer_e5b264d8-a6a0-4130-bc3b-21b6505063c1" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityVoluntaryFilers_dd1dad85-be97-490c-8e39-7f0b71fe2227" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityVoluntaryFilers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityVoluntaryFilers_dd1dad85-be97-490c-8e39-7f0b71fe2227" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_b1f306b8-170c-4031-9c51-440e28632402" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityCurrentReportingStatus_b1f306b8-170c-4031-9c51-440e28632402" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_8eb57d2c-1e95-4173-bd9b-8dbdecfddff4" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityInteractiveDataCurrent_8eb57d2c-1e95-4173-bd9b-8dbdecfddff4" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_42fd5ef9-62cc-4891-8b05-32282b159fbc" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityFilerCategory_42fd5ef9-62cc-4891-8b05-32282b159fbc" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_73e45ce7-9f87-474d-975f-4f4d137e3283" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntitySmallBusiness_73e45ce7-9f87-474d-975f-4f4d137e3283" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_32236214-8c8e-4726-b4b1-a8b57ac6092c" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityEmergingGrowthCompany_32236214-8c8e-4726-b4b1-a8b57ac6092c" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityExTransitionPeriod_37354cf8-4b75-4733-892e-13a9647ef879" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityExTransitionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityExTransitionPeriod_37354cf8-4b75-4733-892e-13a9647ef879" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_IcfrAuditorAttestationFlag_f560935d-8159-44d5-abf4-aa6f8a9a52bb" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_IcfrAuditorAttestationFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_IcfrAuditorAttestationFlag_f560935d-8159-44d5-abf4-aa6f8a9a52bb" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_7bd4edb5-082a-4958-9fa3-2a06aa2174ab" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityShellCompany_7bd4edb5-082a-4958-9fa3-2a06aa2174ab" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityPublicFloat_ddaf496e-234b-442e-9d0f-295158c8f5a3" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityPublicFloat"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityPublicFloat_ddaf496e-234b-442e-9d0f-295158c8f5a3" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_7a1822dc-6b0d-45aa-b7cb-dd27566d7063" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_7a1822dc-6b0d-45aa-b7cb-dd27566d7063" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentsIncorporatedByReferenceTextBlock_9efef3eb-9412-467f-8ef8-ae6fcd4000f0" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentsIncorporatedByReferenceTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_DocumentsIncorporatedByReferenceTextBlock_9efef3eb-9412-467f-8ef8-ae6fcd4000f0" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_78f84e69-47c1-4617-9903-7005dd9ea63b" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_EntityCentralIndexKey_78f84e69-47c1-4617-9903-7005dd9ea63b" xlink:type="arc" order="32"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_47bbffe4-f9c8-40d4-b47d-3df290f645d1" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_AmendmentFlag_47bbffe4-f9c8-40d4-b47d-3df290f645d1" xlink:type="arc" order="33"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_a3c848f7-f2bd-41b8-9702-f39678eaf3f6" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_DocumentFiscalYearFocus_a3c848f7-f2bd-41b8-9702-f39678eaf3f6" xlink:type="arc" order="34"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_e04b2f60-74a8-460d-a7ee-9653120e449b" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_dei_DocumentFiscalPeriodFocus_e04b2f60-74a8-460d-a7ee-9653120e449b" xlink:type="arc" order="35"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_58af3629-4abb-49eb-a2eb-f8d2b9f4c1f5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_1a1ba7d6-98e0-4d89-beae-2ef36c451704" xlink:to="loc_us-gaap_StatementTable_58af3629-4abb-49eb-a2eb-f8d2b9f4c1f5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_ddaa3ff4-4b04-40d5-80ab-ead7cc6c1bda" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_58af3629-4abb-49eb-a2eb-f8d2b9f4c1f5" xlink:to="loc_us-gaap_StatementClassOfStockAxis_ddaa3ff4-4b04-40d5-80ab-ead7cc6c1bda" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_ddaa3ff4-4b04-40d5-80ab-ead7cc6c1bda_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_ddaa3ff4-4b04-40d5-80ab-ead7cc6c1bda" xlink:to="loc_us-gaap_ClassOfStockDomain_ddaa3ff4-4b04-40d5-80ab-ead7cc6c1bda_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_4e2e3003-cca0-400b-b3e8-002893da9144" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_ddaa3ff4-4b04-40d5-80ab-ead7cc6c1bda" xlink:to="loc_us-gaap_ClassOfStockDomain_4e2e3003-cca0-400b-b3e8-002893da9144" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_4c14faff-dbf1-407e-bfce-82f15c1262e8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_4e2e3003-cca0-400b-b3e8-002893da9144" xlink:to="loc_us-gaap_CommonClassAMember_4c14faff-dbf1-407e-bfce-82f15c1262e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_7b014e0b-f464-408c-8899-60120d9637b5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_4e2e3003-cca0-400b-b3e8-002893da9144" xlink:to="loc_us-gaap_CommonClassBMember_7b014e0b-f464-408c-8899-60120d9637b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_00e92429-3936-4ef5-8bbe-613da2d8be08" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_4e2e3003-cca0-400b-b3e8-002893da9144" xlink:to="loc_us-gaap_CommonClassCMember_00e92429-3936-4ef5-8bbe-613da2d8be08" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/ConsolidatedBalanceSheets" xlink:type="simple" xlink:href="zi-20201231.xsd#ConsolidatedBalanceSheets"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/ConsolidatedBalanceSheets" xlink:type="extended" id="ie0c9b714e1244fa394b18c97069c28e9_ConsolidatedBalanceSheets">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_b8906866-d994-4316-a226-a3e2595bf1de" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_48607cf1-f081-4765-8582-b3040b9d807f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b8906866-d994-4316-a226-a3e2595bf1de" xlink:to="loc_us-gaap_AssetsAbstract_48607cf1-f081-4765-8582-b3040b9d807f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_2a540d65-77c4-4a4f-8954-b92ef71d6ed8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_48607cf1-f081-4765-8582-b3040b9d807f" xlink:to="loc_us-gaap_AssetsCurrentAbstract_2a540d65-77c4-4a4f-8954-b92ef71d6ed8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_f0b07b4e-130d-49d8-803d-ffd8165d284c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_2a540d65-77c4-4a4f-8954-b92ef71d6ed8" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_f0b07b4e-130d-49d8-803d-ffd8165d284c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestments_e1a8cf70-b2f7-46cd-856f-3979a8e0a597" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_2a540d65-77c4-4a4f-8954-b92ef71d6ed8" xlink:to="loc_us-gaap_ShortTermInvestments_e1a8cf70-b2f7-46cd-856f-3979a8e0a597" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashCurrent_50bec74d-123e-40c3-a318-2a69cea15104" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedCashCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_2a540d65-77c4-4a4f-8954-b92ef71d6ed8" xlink:to="loc_us-gaap_RestrictedCashCurrent_50bec74d-123e-40c3-a318-2a69cea15104" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_4aab7c40-297a-403f-ad1b-796ea13a04c5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_2a540d65-77c4-4a4f-8954-b92ef71d6ed8" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_4aab7c40-297a-403f-ad1b-796ea13a04c5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_db077a70-dc55-4c18-829a-0f32198b2372" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_2a540d65-77c4-4a4f-8954-b92ef71d6ed8" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_db077a70-dc55-4c18-829a-0f32198b2372" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCostsCurrent_a4e1266d-ea2e-4ebd-ae39-9a3a78f3aea7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCostsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_2a540d65-77c4-4a4f-8954-b92ef71d6ed8" xlink:to="loc_us-gaap_DeferredCostsCurrent_a4e1266d-ea2e-4ebd-ae39-9a3a78f3aea7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesReceivable_4cd15c01-5588-44f2-a36c-1c4e29d418b3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxesReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_2a540d65-77c4-4a4f-8954-b92ef71d6ed8" xlink:to="loc_us-gaap_IncomeTaxesReceivable_4cd15c01-5588-44f2-a36c-1c4e29d418b3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_e6fb6145-9e3c-43ac-a927-24cd33a0dd39" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_2a540d65-77c4-4a4f-8954-b92ef71d6ed8" xlink:to="loc_us-gaap_AssetsCurrent_e6fb6145-9e3c-43ac-a927-24cd33a0dd39" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_d24587bc-40e8-4491-b044-5850c15855c5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_48607cf1-f081-4765-8582-b3040b9d807f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_d24587bc-40e8-4491-b044-5850c15855c5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_bd1315f9-03f2-4a0c-bf87-7ce064451b4e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_48607cf1-f081-4765-8582-b3040b9d807f" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_bd1315f9-03f2-4a0c-bf87-7ce064451b4e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_34979584-7d7b-4de6-a0ba-cb3f5ad13f50" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_48607cf1-f081-4765-8582-b3040b9d807f" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_34979584-7d7b-4de6-a0ba-cb3f5ad13f50" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_a6cf2ee0-82ed-4d39-aa44-a828feda1a05" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_48607cf1-f081-4765-8582-b3040b9d807f" xlink:to="loc_us-gaap_Goodwill_a6cf2ee0-82ed-4d39-aa44-a828feda1a05" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_c11a6165-1639-438e-b301-5430a68693a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_48607cf1-f081-4765-8582-b3040b9d807f" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_c11a6165-1639-438e-b301-5430a68693a0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCosts_758f0df5-26ff-4ccb-96ed-f52b8e736eb8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_48607cf1-f081-4765-8582-b3040b9d807f" xlink:to="loc_us-gaap_DeferredCosts_758f0df5-26ff-4ccb-96ed-f52b8e736eb8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_945df977-b98d-487d-86df-b4425c097ac9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_48607cf1-f081-4765-8582-b3040b9d807f" xlink:to="loc_us-gaap_Assets_945df977-b98d-487d-86df-b4425c097ac9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b8906866-d994-4316-a226-a3e2595bf1de" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_eb5c446e-f07e-40bb-b69f-c584c731cfc9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_eb5c446e-f07e-40bb-b69f-c584c731cfc9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_78fd9efa-a1ce-4b61-b8e7-074b3b709a6a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_eb5c446e-f07e-40bb-b69f-c584c731cfc9" xlink:to="loc_us-gaap_AccountsPayableCurrent_78fd9efa-a1ce-4b61-b8e7-074b3b709a6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_7b708b72-b783-404e-a514-b200d3ae6c4b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_eb5c446e-f07e-40bb-b69f-c584c731cfc9" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_7b708b72-b783-404e-a514-b200d3ae6c4b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_0bac2a07-ef79-4aa2-96a4-37ccbf08901f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_eb5c446e-f07e-40bb-b69f-c584c731cfc9" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_0bac2a07-ef79-4aa2-96a4-37ccbf08901f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedIncomeTaxesCurrent_d97f0e7d-f1ed-475b-ade9-7efbb8a1ad15" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedIncomeTaxesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_eb5c446e-f07e-40bb-b69f-c584c731cfc9" xlink:to="loc_us-gaap_AccruedIncomeTaxesCurrent_d97f0e7d-f1ed-475b-ade9-7efbb8a1ad15" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_62400e0f-7732-4863-ad36-df3983206470" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_eb5c446e-f07e-40bb-b69f-c584c731cfc9" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_62400e0f-7732-4863-ad36-df3983206470" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_f7a2bf63-089c-41e5-aaa9-8a47660ed1d6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_eb5c446e-f07e-40bb-b69f-c584c731cfc9" xlink:to="loc_us-gaap_LongTermDebtCurrent_f7a2bf63-089c-41e5-aaa9-8a47660ed1d6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_d3598107-9107-4aff-8c4e-87e1aa9a3b41" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_eb5c446e-f07e-40bb-b69f-c584c731cfc9" xlink:to="loc_us-gaap_LiabilitiesCurrent_d3598107-9107-4aff-8c4e-87e1aa9a3b41" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_941521cc-2d64-4470-bdae-01d8899efec0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_941521cc-2d64-4470-bdae-01d8899efec0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedIncomeTaxesNoncurrent_6a4b95d0-c64f-40cc-87da-d51bd0ac90ce" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedIncomeTaxesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:to="loc_us-gaap_AccruedIncomeTaxesNoncurrent_6a4b95d0-c64f-40cc-87da-d51bd0ac90ce" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_936ba683-9466-470b-b3de-50b21dc6575f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_936ba683-9466-470b-b3de-50b21dc6575f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_9ac02999-8318-4404-89f5-a7760164c47e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_9ac02999-8318-4404-89f5-a7760164c47e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_275604ce-d4a9-47ed-8078-e97a8e79792d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_275604ce-d4a9-47ed-8078-e97a8e79792d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_d485cea5-b533-4c66-a429-c61ff11c9f47" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_d485cea5-b533-4c66-a429-c61ff11c9f47" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_13ce0aed-73b9-4403-a256-7da192d606db" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:to="loc_us-gaap_Liabilities_13ce0aed-73b9-4403-a256-7da192d606db" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_e58b3bba-9853-41f0-a194-d9de10db6f60" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_e58b3bba-9853-41f0-a194-d9de10db6f60" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_44d2ddea-002c-4a34-8add-9edce5c114d7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:to="loc_us-gaap_CommitmentsAndContingencies_44d2ddea-002c-4a34-8add-9edce5c114d7" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MembersEquityAbstract_183da1af-dc19-4d8a-8f70-83ff34affe21" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MembersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:to="loc_us-gaap_MembersEquityAbstract_183da1af-dc19-4d8a-8f70-83ff34affe21" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MembersCapital_22fbc5d0-a064-4495-ba62-2cab9940d830" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MembersCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_183da1af-dc19-4d8a-8f70-83ff34affe21" xlink:to="loc_us-gaap_MembersCapital_22fbc5d0-a064-4495-ba62-2cab9940d830" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_0610ece8-7dbb-49c7-85a9-0dbca22c2700" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_183da1af-dc19-4d8a-8f70-83ff34affe21" xlink:to="loc_us-gaap_PreferredStockValue_0610ece8-7dbb-49c7-85a9-0dbca22c2700" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_6c4b98fa-3718-46be-98e1-663125dd505e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_183da1af-dc19-4d8a-8f70-83ff34affe21" xlink:to="loc_us-gaap_CommonStockValue_6c4b98fa-3718-46be-98e1-663125dd505e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_d4de8527-d134-4b00-9565-098f7ff77726" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_183da1af-dc19-4d8a-8f70-83ff34affe21" xlink:to="loc_us-gaap_AdditionalPaidInCapital_d4de8527-d134-4b00-9565-098f7ff77726" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_acbe5a30-5d4b-447a-b6d6-2fc9c53c5885" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_183da1af-dc19-4d8a-8f70-83ff34affe21" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_acbe5a30-5d4b-447a-b6d6-2fc9c53c5885" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_dc734356-6666-4a38-bafb-fb331802610e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_183da1af-dc19-4d8a-8f70-83ff34affe21" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_dc734356-6666-4a38-bafb-fb331802610e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_5ca625f1-c832-4549-ad21-de90e9022e4e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_183da1af-dc19-4d8a-8f70-83ff34affe21" xlink:to="loc_us-gaap_MinorityInterest_5ca625f1-c832-4549-ad21-de90e9022e4e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_46430c7b-bcb1-4e1f-bff9-43216b6660b0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_183da1af-dc19-4d8a-8f70-83ff34affe21" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_46430c7b-bcb1-4e1f-bff9-43216b6660b0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MembersEquity_8319a5b3-faa6-433b-be17-47e2d6b2c353" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MembersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MembersEquityAbstract_183da1af-dc19-4d8a-8f70-83ff34affe21" xlink:to="loc_us-gaap_MembersEquity_8319a5b3-faa6-433b-be17-47e2d6b2c353" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_e49c8a22-0297-46e1-96b1-724b9a3d4662" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_340ccbb5-ebf1-4dd9-8fce-b51d5e35f3d9" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_e49c8a22-0297-46e1-96b1-724b9a3d4662" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_be8b1e5a-92df-414c-8f6f-d4a17cb389ce" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_b8906866-d994-4316-a226-a3e2595bf1de" xlink:to="loc_us-gaap_StatementTable_be8b1e5a-92df-414c-8f6f-d4a17cb389ce" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_63e7ebb4-4c05-4f25-96a7-1dc9cf6b69cb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_be8b1e5a-92df-414c-8f6f-d4a17cb389ce" xlink:to="loc_us-gaap_StatementClassOfStockAxis_63e7ebb4-4c05-4f25-96a7-1dc9cf6b69cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_63e7ebb4-4c05-4f25-96a7-1dc9cf6b69cb_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_63e7ebb4-4c05-4f25-96a7-1dc9cf6b69cb" xlink:to="loc_us-gaap_ClassOfStockDomain_63e7ebb4-4c05-4f25-96a7-1dc9cf6b69cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_bb409969-1ed9-48c7-8942-60ea7ba4a835" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_63e7ebb4-4c05-4f25-96a7-1dc9cf6b69cb" xlink:to="loc_us-gaap_ClassOfStockDomain_bb409969-1ed9-48c7-8942-60ea7ba4a835" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_10f727ab-58cb-4657-a152-8cf24ca320d7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_bb409969-1ed9-48c7-8942-60ea7ba4a835" xlink:to="loc_us-gaap_CommonClassAMember_10f727ab-58cb-4657-a152-8cf24ca320d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_daebc9a8-84c2-4c32-8943-08546ed4e9ec" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_bb409969-1ed9-48c7-8942-60ea7ba4a835" xlink:to="loc_us-gaap_CommonClassBMember_daebc9a8-84c2-4c32-8943-08546ed4e9ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_f0967208-4875-4cca-819c-b13855ab3304" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_bb409969-1ed9-48c7-8942-60ea7ba4a835" xlink:to="loc_us-gaap_CommonClassCMember_f0967208-4875-4cca-819c-b13855ab3304" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:type="simple" xlink:href="zi-20201231.xsd#ConsolidatedBalanceSheetsParenthetical"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:type="extended" id="id420594f5cff49b4ae9e6f4320a1260f_ConsolidatedBalanceSheetsParenthetical">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_289171e2-082b-485a-9b40-f6120b9f23ac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_369ddf04-e014-47b6-ab2f-50a64136f72f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_289171e2-082b-485a-9b40-f6120b9f23ac" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_369ddf04-e014-47b6-ab2f-50a64136f72f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_df6178b9-6e84-40dd-976d-2dc48df0db14" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_289171e2-082b-485a-9b40-f6120b9f23ac" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_df6178b9-6e84-40dd-976d-2dc48df0db14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_c4935ec8-3ef5-43c5-a13c-331f9a201dda" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_289171e2-082b-485a-9b40-f6120b9f23ac" xlink:to="loc_us-gaap_CommonStockSharesIssued_c4935ec8-3ef5-43c5-a13c-331f9a201dda" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_e42fa304-19ee-4bf8-895c-3cb7ab046ecc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_289171e2-082b-485a-9b40-f6120b9f23ac" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_e42fa304-19ee-4bf8-895c-3cb7ab046ecc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_0e818873-539b-4db8-b2cb-341156c98f71" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_289171e2-082b-485a-9b40-f6120b9f23ac" xlink:to="loc_us-gaap_StatementTable_0e818873-539b-4db8-b2cb-341156c98f71" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_92db8e1d-f7c6-4a0f-be6a-7e432b4cff37" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_0e818873-539b-4db8-b2cb-341156c98f71" xlink:to="loc_us-gaap_StatementClassOfStockAxis_92db8e1d-f7c6-4a0f-be6a-7e432b4cff37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_92db8e1d-f7c6-4a0f-be6a-7e432b4cff37_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_92db8e1d-f7c6-4a0f-be6a-7e432b4cff37" xlink:to="loc_us-gaap_ClassOfStockDomain_92db8e1d-f7c6-4a0f-be6a-7e432b4cff37_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_874e575c-3db4-4f16-aac0-75bc946148a8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_92db8e1d-f7c6-4a0f-be6a-7e432b4cff37" xlink:to="loc_us-gaap_ClassOfStockDomain_874e575c-3db4-4f16-aac0-75bc946148a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_c889b2d7-acaa-4520-8f2a-6382b53da9cb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_874e575c-3db4-4f16-aac0-75bc946148a8" xlink:to="loc_us-gaap_CommonClassAMember_c889b2d7-acaa-4520-8f2a-6382b53da9cb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_cf7875ff-1890-4e2b-9f49-c05c53f420b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_874e575c-3db4-4f16-aac0-75bc946148a8" xlink:to="loc_us-gaap_CommonClassBMember_cf7875ff-1890-4e2b-9f49-c05c53f420b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_730aefb9-9c71-42e0-9782-77cfd1cc3981" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_874e575c-3db4-4f16-aac0-75bc946148a8" xlink:to="loc_us-gaap_CommonClassCMember_730aefb9-9c71-42e0-9782-77cfd1cc3981" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/ConsolidatedStatementsofOperations" xlink:type="simple" xlink:href="zi-20201231.xsd#ConsolidatedStatementsofOperations"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/ConsolidatedStatementsofOperations" xlink:type="extended" id="i53103a00cebd4a30b72c9acee94ffd9c_ConsolidatedStatementsofOperations"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/ConsolidatedStatementsofOperationsParenthetical" xlink:type="simple" xlink:href="zi-20201231.xsd#ConsolidatedStatementsofOperationsParenthetical"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/ConsolidatedStatementsofOperationsParenthetical" xlink:type="extended" id="if9db2b34ba7642e5b719d0cb2c456092_ConsolidatedStatementsofOperationsParenthetical">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_19e21d4d-a1b3-44ea-acc4-7b151d53cbb8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_41e36257-08b5-45ec-a744-0251c1d291e8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_19e21d4d-a1b3-44ea-acc4-7b151d53cbb8" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_41e36257-08b5-45ec-a744-0251c1d291e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_8e3b7307-b0ed-4388-9612-31f3dca9fdb0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_19e21d4d-a1b3-44ea-acc4-7b151d53cbb8" xlink:to="loc_us-gaap_StatementTable_8e3b7307-b0ed-4388-9612-31f3dca9fdb0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_c7b75632-cadb-415c-b070-63790b0a9d37" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_8e3b7307-b0ed-4388-9612-31f3dca9fdb0" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_c7b75632-cadb-415c-b070-63790b0a9d37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_c7b75632-cadb-415c-b070-63790b0a9d37_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_c7b75632-cadb-415c-b070-63790b0a9d37" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_c7b75632-cadb-415c-b070-63790b0a9d37_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_02e4da26-213a-4ae3-8832-0d7ceecb4dd9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_c7b75632-cadb-415c-b070-63790b0a9d37" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_02e4da26-213a-4ae3-8832-0d7ceecb4dd9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_0518c231-26c2-41b9-bb83-0c9b235e6b81" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_02e4da26-213a-4ae3-8832-0d7ceecb4dd9" xlink:to="loc_us-gaap_CostOfSalesMember_0518c231-26c2-41b9-bb83-0c9b235e6b81" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_99e5db68-28e4-4a40-9050-dfaba12097cb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SellingAndMarketingExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_02e4da26-213a-4ae3-8832-0d7ceecb4dd9" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_99e5db68-28e4-4a40-9050-dfaba12097cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_296ffe24-a0ca-4b35-b18b-a7a87757a7fe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_02e4da26-213a-4ae3-8832-0d7ceecb4dd9" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_296ffe24-a0ca-4b35-b18b-a7a87757a7fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_d982969a-ee64-4fe8-b6ef-c8a4c405f336" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_02e4da26-213a-4ae3-8832-0d7ceecb4dd9" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_d982969a-ee64-4fe8-b6ef-c8a4c405f336" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/ConsolidatedStatementsofComprehensiveIncomeLoss" xlink:type="simple" xlink:href="zi-20201231.xsd#ConsolidatedStatementsofComprehensiveIncomeLoss"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/ConsolidatedStatementsofComprehensiveIncomeLoss" xlink:type="extended" id="if7661fb7998542c2a853f6a5fcb8c88f_ConsolidatedStatementsofComprehensiveIncomeLoss"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/ConsolidatedStatementsofChangesinEquityDeficit" xlink:type="simple" xlink:href="zi-20201231.xsd#ConsolidatedStatementsofChangesinEquityDeficit"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/ConsolidatedStatementsofChangesinEquityDeficit" xlink:type="extended" id="i47c5f7a4c3054358ad66b4bb4fe8f367_ConsolidatedStatementsofChangesinEquityDeficit">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_bc89879d-55bf-40f3-a19e-e0979db6cd3b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdateExtensibleList_bbf01bfc-4922-4386-8209-bc569a2805f6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountingStandardsUpdateExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bc89879d-55bf-40f3-a19e-e0979db6cd3b" xlink:to="loc_us-gaap_AccountingStandardsUpdateExtensibleList_bbf01bfc-4922-4386-8209-bc569a2805f6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bc89879d-55bf-40f3-a19e-e0979db6cd3b" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MembersEquity_4c7053ef-5165-45da-b195-eda897993f45" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MembersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_MembersEquity_4c7053ef-5165-45da-b195-eda897993f45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_a00957b1-bf10-4671-b685-9b65f71613c2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_a00957b1-bf10-4671-b685-9b65f71613c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_82c60416-8fb2-4fac-8846-8bbf137df579" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_82c60416-8fb2-4fac-8846-8bbf137df579" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_NetIncomeLossAttributableToParentPriorToReorganization_85334d20-95b3-4222-ab11-74ed01071a74" xlink:href="zi-20201231.xsd#zi_NetIncomeLossAttributableToParentPriorToReorganization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_NetIncomeLossAttributableToParentPriorToReorganization_85334d20-95b3-4222-ab11-74ed01071a74" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_72e4e720-5c9b-43e0-a7ac-8c2c5e2dfe66" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_ProfitLoss_72e4e720-5c9b-43e0-a7ac-8c2c5e2dfe66" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_2e15bc07-3831-4361-87b1-b2736d4087ab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_2e15bc07-3831-4361-87b1-b2736d4087ab" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_OtherComprehensiveIncomeLossNetOfTaxPriorToReorganization_ecdae8f7-8c81-4a38-aa49-c31b4958adb0" xlink:href="zi-20201231.xsd#zi_OtherComprehensiveIncomeLossNetOfTaxPriorToReorganization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_OtherComprehensiveIncomeLossNetOfTaxPriorToReorganization_ecdae8f7-8c81-4a38-aa49-c31b4958adb0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionMadeToLimitedLiabilityCompanyLLCMemberCashDistributionsDeclared_9b99f364-5f7d-4f1b-99d9-a8745fd0f556" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DistributionMadeToLimitedLiabilityCompanyLLCMemberCashDistributionsDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_DistributionMadeToLimitedLiabilityCompanyLLCMemberCashDistributionsDeclared_9b99f364-5f7d-4f1b-99d9-a8745fd0f556" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_APICShareBasedCompensationIncreaseForCostOfRecognitionPriorToReorganization_b3d6a554-6815-471b-92c9-7f0463b1dacf" xlink:href="zi-20201231.xsd#zi_APICShareBasedCompensationIncreaseForCostOfRecognitionPriorToReorganization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_APICShareBasedCompensationIncreaseForCostOfRecognitionPriorToReorganization_b3d6a554-6815-471b-92c9-7f0463b1dacf" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_StockIssuedDuringPeriodNoncontrollingInterestIncreaseFromBusinessCombination_7e5b9d2e-475a-4a57-8a0c-ec99a98858a7" xlink:href="zi-20201231.xsd#zi_StockIssuedDuringPeriodNoncontrollingInterestIncreaseFromBusinessCombination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_StockIssuedDuringPeriodNoncontrollingInterestIncreaseFromBusinessCombination_7e5b9d2e-475a-4a57-8a0c-ec99a98858a7" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_StockIssuedDuringPeriodValueNoncontrollingInterestIncreaseFromBusinessCombination_3679f589-d053-4cd6-a9c2-0d50397f85de" xlink:href="zi-20201231.xsd#zi_StockIssuedDuringPeriodValueNoncontrollingInterestIncreaseFromBusinessCombination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_StockIssuedDuringPeriodValueNoncontrollingInterestIncreaseFromBusinessCombination_3679f589-d053-4cd6-a9c2-0d50397f85de" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_f991aeb2-be4d-4662-b1de-311138cac2f5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_f991aeb2-be4d-4662-b1de-311138cac2f5" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_510a2303-21da-4344-9785-a1d9bb13aab7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_510a2303-21da-4344-9785-a1d9bb13aab7" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_StockIssuedDuringPeriodSharesExchange_e7a64109-b8fc-4f9d-be76-6991c6eb4c91" xlink:href="zi-20201231.xsd#zi_StockIssuedDuringPeriodSharesExchange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_StockIssuedDuringPeriodSharesExchange_e7a64109-b8fc-4f9d-be76-6991c6eb4c91" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_StockIssuedDuringPeriodValueExchange_b75b2bec-36dc-4121-a8db-5a3c3f04bc33" xlink:href="zi-20201231.xsd#zi_StockIssuedDuringPeriodValueExchange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_StockIssuedDuringPeriodValueExchange_b75b2bec-36dc-4121-a8db-5a3c3f04bc33" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_StockIssuedDuringPeriodSharesPurchaseOfUnits_8f775891-44bc-4ca2-ae1d-f31febc5c64b" xlink:href="zi-20201231.xsd#zi_StockIssuedDuringPeriodSharesPurchaseOfUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_StockIssuedDuringPeriodSharesPurchaseOfUnits_8f775891-44bc-4ca2-ae1d-f31febc5c64b" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_StockIssuedDuringPeriodValuePurchaseOfUnits_ef205810-1872-4e2c-a354-55d01f4cba2b" xlink:href="zi-20201231.xsd#zi_StockIssuedDuringPeriodValuePurchaseOfUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_StockIssuedDuringPeriodValuePurchaseOfUnits_ef205810-1872-4e2c-a354-55d01f4cba2b" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_StockholdersEquityIncreaseDecreaseInSharesDueToExchange_4ce4b39c-40c2-4108-8771-651dbc59a279" xlink:href="zi-20201231.xsd#zi_StockholdersEquityIncreaseDecreaseInSharesDueToExchange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_StockholdersEquityIncreaseDecreaseInSharesDueToExchange_4ce4b39c-40c2-4108-8771-651dbc59a279" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_StockholdersEquityIncreaseDecreaseInSharesDueToExchangeValue_e3d2657c-816b-4582-9592-a979e423850f" xlink:href="zi-20201231.xsd#zi_StockholdersEquityIncreaseDecreaseInSharesDueToExchangeValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_StockholdersEquityIncreaseDecreaseInSharesDueToExchangeValue_e3d2657c-816b-4582-9592-a979e423850f" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_5317cd1d-b39b-462a-a3a0-3c02d48ab697" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_5317cd1d-b39b-462a-a3a0-3c02d48ab697" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_4dd5527a-ca10-4a60-aa37-d30a4c55656e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_4dd5527a-ca10-4a60-aa37-d30a4c55656e" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_65c5d433-e924-4f21-9134-66cca53e2d19" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_65c5d433-e924-4f21-9134-66cca53e2d19" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_451572b1-5a23-4753-a2ba-a82231693adc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_451572b1-5a23-4753-a2ba-a82231693adc" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_ee913630-25d7-493f-b90d-1f362e391d52" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_ee913630-25d7-493f-b90d-1f362e391d52" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_8314ef3e-1205-4088-86dc-16065c18526e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_8314ef3e-1205-4088-86dc-16065c18526e" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited_6751c6cb-3d11-4df0-a01a-d57172bd49d7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited_6751c6cb-3d11-4df0-a01a-d57172bd49d7" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures_0d72dc73-add2-41a3-8aa1-1060790b3f56" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures_0d72dc73-add2-41a3-8aa1-1060790b3f56" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockAccretionOfRedemptionDiscount_6d8edd58-543e-476e-838a-c101e93c6d31" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockAccretionOfRedemptionDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_PreferredStockAccretionOfRedemptionDiscount_6d8edd58-543e-476e-838a-c101e93c6d31" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_NetIncomeLossAttributableToParentSubsequentToReorganization_b6463ffe-9c79-46a6-86e3-8cdc18fdff97" xlink:href="zi-20201231.xsd#zi_NetIncomeLossAttributableToParentSubsequentToReorganization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_NetIncomeLossAttributableToParentSubsequentToReorganization_b6463ffe-9c79-46a6-86e3-8cdc18fdff97" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_OtherComprehensiveIncomeLossNetOfTaxSubsequentToReorganization_66f54012-b9ac-45ac-8138-e444193c1fdd" xlink:href="zi-20201231.xsd#zi_OtherComprehensiveIncomeLossNetOfTaxSubsequentToReorganization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_OtherComprehensiveIncomeLossNetOfTaxSubsequentToReorganization_66f54012-b9ac-45ac-8138-e444193c1fdd" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_APICShareBasedCompensationIncreaseForCostOfRecognitionSubsequentToReorganization_dfaa53b2-3768-4252-8d05-81c9637d9eaf" xlink:href="zi-20201231.xsd#zi_APICShareBasedCompensationIncreaseForCostOfRecognitionSubsequentToReorganization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_APICShareBasedCompensationIncreaseForCostOfRecognitionSubsequentToReorganization_dfaa53b2-3768-4252-8d05-81c9637d9eaf" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_8fbcbf5a-330e-4ac1-9f05-db3540ac3df8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_8fbcbf5a-330e-4ac1-9f05-db3540ac3df8" xlink:type="arc" order="32"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_CashPaidForRepurchaseOfUnits_ca7ff348-8c18-4875-ab9c-ca40afdafdbd" xlink:href="zi-20201231.xsd#zi_CashPaidForRepurchaseOfUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_zi_CashPaidForRepurchaseOfUnits_ca7ff348-8c18-4875-ab9c-ca40afdafdbd" xlink:type="arc" order="33"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_92cb9d83-ea76-4abf-9e9c-cdb56bb1e704" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_92cb9d83-ea76-4abf-9e9c-cdb56bb1e704" xlink:type="arc" order="34"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_19c1da89-8f57-480f-9c06-980e030a736e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_fe5a28c1-6ac2-42dd-9ca0-b00934b56cf4" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_19c1da89-8f57-480f-9c06-980e030a736e" xlink:type="arc" order="35"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MembersEquity_17515eaf-9daa-4097-bad6-c5eb57f75702" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MembersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_74b4713e-2fe1-4c9a-b16d-efc90785ce88" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9f2e7842-d23d-4ce6-9dfe-43c0729c4591" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_bd5394b0-ed36-4da3-9220-df7f88ebefc5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_bc89879d-55bf-40f3-a19e-e0979db6cd3b" xlink:to="loc_us-gaap_StatementTable_bd5394b0-ed36-4da3-9220-df7f88ebefc5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_19ef2bc2-4680-4d82-985e-b8bd4264ecc0" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_bd5394b0-ed36-4da3-9220-df7f88ebefc5" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_19ef2bc2-4680-4d82-985e-b8bd4264ecc0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_19ef2bc2-4680-4d82-985e-b8bd4264ecc0_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_19ef2bc2-4680-4d82-985e-b8bd4264ecc0" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_19ef2bc2-4680-4d82-985e-b8bd4264ecc0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_6b91f596-d5c7-446f-ba0c-7800f67bebc2" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_19ef2bc2-4680-4d82-985e-b8bd4264ecc0" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_6b91f596-d5c7-446f-ba0c-7800f67bebc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_cf4c2b7c-37ca-45f0-bb71-9b83189ec6ce" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_6b91f596-d5c7-446f-ba0c-7800f67bebc2" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_cf4c2b7c-37ca-45f0-bb71-9b83189ec6ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_d5199c75-65af-4bc7-9612-c732f03db358" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_bd5394b0-ed36-4da3-9220-df7f88ebefc5" xlink:to="loc_dei_LegalEntityAxis_d5199c75-65af-4bc7-9612-c732f03db358" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_d5199c75-65af-4bc7-9612-c732f03db358_default" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_d5199c75-65af-4bc7-9612-c732f03db358" xlink:to="loc_dei_EntityDomain_d5199c75-65af-4bc7-9612-c732f03db358_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_7912cde1-9994-4480-ab7e-811116af4948" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_d5199c75-65af-4bc7-9612-c732f03db358" xlink:to="loc_dei_EntityDomain_7912cde1-9994-4480-ab7e-811116af4948" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreAcquisitionZoomInformationIncMember_96fe8c03-762e-4992-a7b1-52facdd10669" xlink:href="zi-20201231.xsd#zi_PreAcquisitionZoomInformationIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7912cde1-9994-4480-ab7e-811116af4948" xlink:to="loc_zi_PreAcquisitionZoomInformationIncMember_96fe8c03-762e-4992-a7b1-52facdd10669" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_f72e0d20-1ed4-427a-9a1b-f75bfd7b1b9f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_bd5394b0-ed36-4da3-9220-df7f88ebefc5" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_f72e0d20-1ed4-427a-9a1b-f75bfd7b1b9f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_f72e0d20-1ed4-427a-9a1b-f75bfd7b1b9f_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f72e0d20-1ed4-427a-9a1b-f75bfd7b1b9f" xlink:to="loc_us-gaap_EquityComponentDomain_f72e0d20-1ed4-427a-9a1b-f75bfd7b1b9f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_96158824-e630-4453-8efc-0c6da5622054" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f72e0d20-1ed4-427a-9a1b-f75bfd7b1b9f" xlink:to="loc_us-gaap_EquityComponentDomain_96158824-e630-4453-8efc-0c6da5622054" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_1cd0b9e6-6e62-4850-9bfc-2af064b22105" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_96158824-e630-4453-8efc-0c6da5622054" xlink:to="loc_us-gaap_CommonStockMember_1cd0b9e6-6e62-4850-9bfc-2af064b22105" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_b1ff2659-1442-4058-bfff-caaf83721b0d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_96158824-e630-4453-8efc-0c6da5622054" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_b1ff2659-1442-4058-bfff-caaf83721b0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_21d2d5b1-b1ff-454a-acd4-c1be82a7f9df" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_96158824-e630-4453-8efc-0c6da5622054" xlink:to="loc_us-gaap_RetainedEarningsMember_21d2d5b1-b1ff-454a-acd4-c1be82a7f9df" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_412f650c-6f43-4448-af59-688ecdd2ea74" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_96158824-e630-4453-8efc-0c6da5622054" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_412f650c-6f43-4448-af59-688ecdd2ea74" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_3c5a10b6-535b-4195-9f24-3a0c62739a75" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_96158824-e630-4453-8efc-0c6da5622054" xlink:to="loc_us-gaap_NoncontrollingInterestMember_3c5a10b6-535b-4195-9f24-3a0c62739a75" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_613af4f7-2193-424d-bad3-aea86fdd8d38" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_bd5394b0-ed36-4da3-9220-df7f88ebefc5" xlink:to="loc_us-gaap_StatementClassOfStockAxis_613af4f7-2193-424d-bad3-aea86fdd8d38" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_613af4f7-2193-424d-bad3-aea86fdd8d38_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_613af4f7-2193-424d-bad3-aea86fdd8d38" xlink:to="loc_us-gaap_ClassOfStockDomain_613af4f7-2193-424d-bad3-aea86fdd8d38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_21ae5b6e-54f8-4396-b2dd-6f6d599e4425" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_613af4f7-2193-424d-bad3-aea86fdd8d38" xlink:to="loc_us-gaap_ClassOfStockDomain_21ae5b6e-54f8-4396-b2dd-6f6d599e4425" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_111fba9f-35bb-43d2-aade-50475fe5af1e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_21ae5b6e-54f8-4396-b2dd-6f6d599e4425" xlink:to="loc_us-gaap_CommonClassAMember_111fba9f-35bb-43d2-aade-50475fe5af1e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_75be1afe-e96d-49f1-b50f-8e1c506d05fb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_21ae5b6e-54f8-4396-b2dd-6f6d599e4425" xlink:to="loc_us-gaap_CommonClassBMember_75be1afe-e96d-49f1-b50f-8e1c506d05fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_c6c3bc81-7b1d-4dca-bd3d-b6a37d422fdd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_21ae5b6e-54f8-4396-b2dd-6f6d599e4425" xlink:to="loc_us-gaap_CommonClassCMember_c6c3bc81-7b1d-4dca-bd3d-b6a37d422fdd" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/ConsolidatedStatementsofCashFlows" xlink:type="simple" xlink:href="zi-20201231.xsd#ConsolidatedStatementsofCashFlows"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/ConsolidatedStatementsofCashFlows" xlink:type="extended" id="idfa4829f083a42819e934c19a2e78381_ConsolidatedStatementsofCashFlows"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/OrganizationandBackground" xlink:type="simple" xlink:href="zi-20201231.xsd#OrganizationandBackground"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/OrganizationandBackground" xlink:type="extended" id="if7f3924c5ad242a08b297f67f0086beb_OrganizationandBackground"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/OrganizationandBackgroundDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#OrganizationandBackgroundDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/OrganizationandBackgroundDetails" xlink:type="extended" id="i9a7126577868498d821b1538387f10e3_OrganizationandBackgroundDetails">
    <link:loc xlink:type="locator" xlink:label="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:href="zi-20201231.xsd#zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_NumberOfOffices_68a54399-cdea-4dd0-95df-9b33d4baeaa9" xlink:href="zi-20201231.xsd#zi_NumberOfOffices"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:to="loc_zi_NumberOfOffices_68a54399-cdea-4dd0-95df-9b33d4baeaa9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_69dd15c2-036d-4bcd-a9e2-c626fed4f2a9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_69dd15c2-036d-4bcd-a9e2-c626fed4f2a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_6e5af20b-99bd-47fe-b7f8-db3773019330" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_6e5af20b-99bd-47fe-b7f8-db3773019330" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_5b8499ff-4013-4a7f-b8ed-008e714321c8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:to="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_5b8499ff-4013-4a7f-b8ed-008e714321c8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_2c114730-59af-4303-9a92-764ecb8f2838" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_2c114730-59af-4303-9a92-764ecb8f2838" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_f3c2e703-bd9a-497a-93f0-c7f0c2744384" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_f3c2e703-bd9a-497a-93f0-c7f0c2744384" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities_1d2eef7a-509b-46e5-840e-ff1096787938" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:to="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities_1d2eef7a-509b-46e5-840e-ff1096787938" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_c2b81f6c-1fb4-4941-87fb-3b77cd0dfb30" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityNoteStockSplitConversionRatio1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:to="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_c2b81f6c-1fb4-4941-87fb-3b77cd0dfb30" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_e0e5d79f-3116-498b-bb48-3c75e03b3a46" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_e0e5d79f-3116-498b-bb48-3c75e03b3a46" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_EquityMethodInvestmentOwnershipPercentageOfUnits_b20f6ef8-7349-42d5-b7ea-0b62e504659f" xlink:href="zi-20201231.xsd#zi_EquityMethodInvestmentOwnershipPercentageOfUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:to="loc_zi_EquityMethodInvestmentOwnershipPercentageOfUnits_b20f6ef8-7349-42d5-b7ea-0b62e504659f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_NumberOfTaxReceivableAgreements_8ad9c12f-1579-45d9-95f0-94596e501e24" xlink:href="zi-20201231.xsd#zi_NumberOfTaxReceivableAgreements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:to="loc_zi_NumberOfTaxReceivableAgreements_8ad9c12f-1579-45d9-95f0-94596e501e24" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_43bae294-c5ce-43a5-8d40-832dbe9ae714" xlink:href="zi-20201231.xsd#zi_OrganizationConsolidationAndPresentationOfFinancialStatementsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_9b8f5bfe-e03b-49ac-bebc-91953c560305" xlink:to="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_43bae294-c5ce-43a5-8d40-832dbe9ae714" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_48c1b7c9-262c-4fa5-a8c7-9cedaa9921c5" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_43bae294-c5ce-43a5-8d40-832dbe9ae714" xlink:to="loc_srt_StatementGeographicalAxis_48c1b7c9-262c-4fa5-a8c7-9cedaa9921c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_48c1b7c9-262c-4fa5-a8c7-9cedaa9921c5_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_48c1b7c9-262c-4fa5-a8c7-9cedaa9921c5" xlink:to="loc_srt_SegmentGeographicalDomain_48c1b7c9-262c-4fa5-a8c7-9cedaa9921c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_13955ad2-3181-4fc0-8a6b-9f5a3ffd615b" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_48c1b7c9-262c-4fa5-a8c7-9cedaa9921c5" xlink:to="loc_srt_SegmentGeographicalDomain_13955ad2-3181-4fc0-8a6b-9f5a3ffd615b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_52567d7c-b7b3-45e7-86dd-4b97e6839698" xlink:href="https://xbrl.sec.gov/country/2020/country-2020-01-31.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_13955ad2-3181-4fc0-8a6b-9f5a3ffd615b" xlink:to="loc_country_US_52567d7c-b7b3-45e7-86dd-4b97e6839698" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_IL_cd1aa607-aa58-4c38-be7c-a93bdd36a443" xlink:href="https://xbrl.sec.gov/country/2020/country-2020-01-31.xsd#country_IL"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_13955ad2-3181-4fc0-8a6b-9f5a3ffd615b" xlink:to="loc_country_IL_cd1aa607-aa58-4c38-be7c-a93bdd36a443" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_1fe35c95-f7c4-4121-9f4a-f36e353aa462" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_43bae294-c5ce-43a5-8d40-832dbe9ae714" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_1fe35c95-f7c4-4121-9f4a-f36e353aa462" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_1fe35c95-f7c4-4121-9f4a-f36e353aa462_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_1fe35c95-f7c4-4121-9f4a-f36e353aa462" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_1fe35c95-f7c4-4121-9f4a-f36e353aa462_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_5b283e60-acb9-4aac-b3b2-8966a0a1327f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_1fe35c95-f7c4-4121-9f4a-f36e353aa462" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_5b283e60-acb9-4aac-b3b2-8966a0a1327f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IPOMember_517c34d3-70da-4312-be16-f8aeaf1982de" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IPOMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_5b283e60-acb9-4aac-b3b2-8966a0a1327f" xlink:to="loc_us-gaap_IPOMember_517c34d3-70da-4312-be16-f8aeaf1982de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_a7dd0211-0ffd-485b-bdc7-1fc947e53084" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_43bae294-c5ce-43a5-8d40-832dbe9ae714" xlink:to="loc_us-gaap_StatementClassOfStockAxis_a7dd0211-0ffd-485b-bdc7-1fc947e53084" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a7dd0211-0ffd-485b-bdc7-1fc947e53084_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a7dd0211-0ffd-485b-bdc7-1fc947e53084" xlink:to="loc_us-gaap_ClassOfStockDomain_a7dd0211-0ffd-485b-bdc7-1fc947e53084_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_bda52ca7-b24b-4111-84d8-30eeee3a8434" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a7dd0211-0ffd-485b-bdc7-1fc947e53084" xlink:to="loc_us-gaap_ClassOfStockDomain_bda52ca7-b24b-4111-84d8-30eeee3a8434" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_c4437914-effa-40cc-adde-239a18906357" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_bda52ca7-b24b-4111-84d8-30eeee3a8434" xlink:to="loc_us-gaap_CommonClassAMember_c4437914-effa-40cc-adde-239a18906357" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_4df58c1c-ad15-40b9-9cc6-b9f7adb7be20" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_43bae294-c5ce-43a5-8d40-832dbe9ae714" xlink:to="loc_dei_LegalEntityAxis_4df58c1c-ad15-40b9-9cc6-b9f7adb7be20" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_4df58c1c-ad15-40b9-9cc6-b9f7adb7be20_default" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_4df58c1c-ad15-40b9-9cc6-b9f7adb7be20" xlink:to="loc_dei_EntityDomain_4df58c1c-ad15-40b9-9cc6-b9f7adb7be20_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_36a71901-b61b-403e-8bd4-b5f5dd83c655" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_4df58c1c-ad15-40b9-9cc6-b9f7adb7be20" xlink:to="loc_dei_EntityDomain_36a71901-b61b-403e-8bd4-b5f5dd83c655" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ZoomInfoHoldCoMember_5bb98384-c98e-4675-8c78-9085b48fe291" xlink:href="zi-20201231.xsd#zi_ZoomInfoHoldCoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_36a71901-b61b-403e-8bd4-b5f5dd83c655" xlink:to="loc_zi_ZoomInfoHoldCoMember_5bb98384-c98e-4675-8c78-9085b48fe291" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ZoomInfoOpCoMember_77553530-ae90-4268-9094-0a9a83d3abc2" xlink:href="zi-20201231.xsd#zi_ZoomInfoOpCoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_36a71901-b61b-403e-8bd4-b5f5dd83c655" xlink:to="loc_zi_ZoomInfoOpCoMember_77553530-ae90-4268-9094-0a9a83d3abc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_6679fd9a-b4f1-428a-a1a0-c5371e2dd371" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_43bae294-c5ce-43a5-8d40-832dbe9ae714" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_6679fd9a-b4f1-428a-a1a0-c5371e2dd371" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6679fd9a-b4f1-428a-a1a0-c5371e2dd371_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6679fd9a-b4f1-428a-a1a0-c5371e2dd371" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6679fd9a-b4f1-428a-a1a0-c5371e2dd371_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6d067a9e-ffc3-43f5-80b8-0787d2bec253" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6679fd9a-b4f1-428a-a1a0-c5371e2dd371" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6d067a9e-ffc3-43f5-80b8-0787d2bec253" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BlockerMergersMember_03e944e7-e083-4bd6-92c1-13c0b9efccb8" xlink:href="zi-20201231.xsd#zi_BlockerMergersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6d067a9e-ffc3-43f5-80b8-0787d2bec253" xlink:to="loc_zi_BlockerMergersMember_03e944e7-e083-4bd6-92c1-13c0b9efccb8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_fe30cd95-5550-4cb1-8fd5-2075269d0a4b" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_43bae294-c5ce-43a5-8d40-832dbe9ae714" xlink:to="loc_srt_OwnershipAxis_fe30cd95-5550-4cb1-8fd5-2075269d0a4b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_fe30cd95-5550-4cb1-8fd5-2075269d0a4b_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_fe30cd95-5550-4cb1-8fd5-2075269d0a4b" xlink:to="loc_srt_OwnershipDomain_fe30cd95-5550-4cb1-8fd5-2075269d0a4b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_5e5677f0-7818-4e30-a6ca-ffb989d46c92" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_fe30cd95-5550-4cb1-8fd5-2075269d0a4b" xlink:to="loc_srt_OwnershipDomain_5e5677f0-7818-4e30-a6ca-ffb989d46c92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ZoomInfoHoldCoMember_aba0146e-27ca-4376-92eb-1dc124f44fab" xlink:href="zi-20201231.xsd#zi_ZoomInfoHoldCoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_5e5677f0-7818-4e30-a6ca-ffb989d46c92" xlink:to="loc_zi_ZoomInfoHoldCoMember_aba0146e-27ca-4376-92eb-1dc124f44fab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_011e2cd2-1d5e-4a83-9e5e-fa47c63191dc" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_zi_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_43bae294-c5ce-43a5-8d40-832dbe9ae714" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_011e2cd2-1d5e-4a83-9e5e-fa47c63191dc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_011e2cd2-1d5e-4a83-9e5e-fa47c63191dc_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_011e2cd2-1d5e-4a83-9e5e-fa47c63191dc" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_011e2cd2-1d5e-4a83-9e5e-fa47c63191dc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_c9ef0f93-053c-4ee7-908d-f879c574345c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_011e2cd2-1d5e-4a83-9e5e-fa47c63191dc" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_c9ef0f93-053c-4ee7-908d-f879c574345c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ZoomInfoOpCoMember_bd5622a9-fd33-47c2-bd3a-b8b26c058d3c" xlink:href="zi-20201231.xsd#zi_ZoomInfoOpCoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_c9ef0f93-053c-4ee7-908d-f879c574345c" xlink:to="loc_zi_ZoomInfoOpCoMember_bd5622a9-fd33-47c2-bd3a-b8b26c058d3c" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/BasisofPresentationandSummaryofSignificantAccountingPolicies" xlink:type="simple" xlink:href="zi-20201231.xsd#BasisofPresentationandSummaryofSignificantAccountingPolicies"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/BasisofPresentationandSummaryofSignificantAccountingPolicies" xlink:type="extended" id="i119f3e71363a4aaf8a0a4f246479c321_BasisofPresentationandSummaryofSignificantAccountingPolicies"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesPolicies" xlink:type="simple" xlink:href="zi-20201231.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesPolicies"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesPolicies" xlink:type="extended" id="i6f86c17fcb7244b284c2d33aa06e28da_BasisofPresentationandSummaryofSignificantAccountingPoliciesPolicies"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesDetails" xlink:type="extended" id="id354f60c0fa543a7bab3fb8d5fab2913_BasisofPresentationandSummaryofSignificantAccountingPoliciesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:href="zi-20201231.xsd#zi_AccountingPoliciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_RevenueFromContractWithCustomerTermOfContract_d4d32df6-4d21-47c2-bfb2-0e667b5d0c9b" xlink:href="zi-20201231.xsd#zi_RevenueFromContractWithCustomerTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_zi_RevenueFromContractWithCustomerTermOfContract_d4d32df6-4d21-47c2-bfb2-0e667b5d0c9b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_bd2fdc69-4b1f-45c3-b1ec-99acfa664344" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_bd2fdc69-4b1f-45c3-b1ec-99acfa664344" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_DeferredSalesCommissionsAmortizationPeriod_db2b9577-3560-4c10-8b3c-ef069d2694d3" xlink:href="zi-20201231.xsd#zi_DeferredSalesCommissionsAmortizationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_zi_DeferredSalesCommissionsAmortizationPeriod_db2b9577-3560-4c10-8b3c-ef069d2694d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedSalesCommissionCurrentAndNoncurrent_31a63e9c-bf09-4033-b096-055354d172b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedSalesCommissionCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_AccruedSalesCommissionCurrentAndNoncurrent_31a63e9c-bf09-4033-b096-055354d172b9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostGross_4263558b-e22c-49be-a118-8bf0f42711a2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CapitalizedContractCostGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_CapitalizedContractCostGross_4263558b-e22c-49be-a118-8bf0f42711a2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostAmortization_effd0b1c-4fb9-44f3-be5d-529326ede6fd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CapitalizedContractCostAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_CapitalizedContractCostAmortization_effd0b1c-4fb9-44f3-be5d-529326ede6fd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostNet_a48a56ec-5bb6-45e9-bdfc-de6e42741562" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CapitalizedContractCostNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_CapitalizedContractCostNet_a48a56ec-5bb6-45e9-bdfc-de6e42741562" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostImpairmentLoss_994c6741-4bd1-491f-8327-0d48954683bf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CapitalizedContractCostImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_CapitalizedContractCostImpairmentLoss_994c6741-4bd1-491f-8327-0d48954683bf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvertisingExpense_429ca6a7-8902-43d5-a90b-62d1428a5cd5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdvertisingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_AdvertisingExpense_429ca6a7-8902-43d5-a90b-62d1428a5cd5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportingUnits_46f7a347-a4ea-4467-95ae-5b1b9ab7797c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfReportingUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_NumberOfReportingUnits_46f7a347-a4ea-4467-95ae-5b1b9ab7797c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_ac381cde-371f-43a6-b738-a7858b745ae5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_ac381cde-371f-43a6-b738-a7858b745ae5" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_ff3613ea-f525-4d46-9bbc-3d29f28c35e5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_ff3613ea-f525-4d46-9bbc-3d29f28c35e5" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_9b0ac6e7-e203-4992-85f0-59a36a820323" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_9b0ac6e7-e203-4992-85f0-59a36a820323" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_NumberOfTaxReceivableAgreements_afdc659d-bef2-4ff9-aa7f-29f373c1daa5" xlink:href="zi-20201231.xsd#zi_NumberOfTaxReceivableAgreements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_zi_NumberOfTaxReceivableAgreements_afdc659d-bef2-4ff9-aa7f-29f373c1daa5" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PaymentProvidedAsPercentOfNetCashSavings_c76f9914-5a6e-4bbd-8c7f-e364a1d94cac" xlink:href="zi-20201231.xsd#zi_PaymentProvidedAsPercentOfNetCashSavings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_zi_PaymentProvidedAsPercentOfNetCashSavings_c76f9914-5a6e-4bbd-8c7f-e364a1d94cac" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BenefitRetainedAsPercentOfNetCashSavings_26aa8871-d59e-4ba9-92c3-6620750ded10" xlink:href="zi-20201231.xsd#zi_BenefitRetainedAsPercentOfNetCashSavings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_zi_BenefitRetainedAsPercentOfNetCashSavings_26aa8871-d59e-4ba9-92c3-6620750ded10" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_e6bbbfdc-1ec5-4830-a793-eb883d430a5a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_e6bbbfdc-1ec5-4830-a793-eb883d430a5a" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_57cec6b1-789a-40cb-80d6-8af6843798bd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_57cec6b1-789a-40cb-80d6-8af6843798bd" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_52b30db1-97df-47e2-89d3-e08e0e5315a1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_52b30db1-97df-47e2-89d3-e08e0e5315a1" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_e43b4906-bfb2-4e27-9dc9-73e4685bbf43" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_e43b4906-bfb2-4e27-9dc9-73e4685bbf43" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_DefinedContributionPlanVestingTerm_51f53a17-91c5-4bcf-b516-a2fbc720a1fb" xlink:href="zi-20201231.xsd#zi_DefinedContributionPlanVestingTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_zi_DefinedContributionPlanVestingTerm_51f53a17-91c5-4bcf-b516-a2fbc720a1fb" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_AccountingPoliciesTable_45b89b11-0156-439f-8b42-901ff038bce8" xlink:href="zi-20201231.xsd#zi_AccountingPoliciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_zi_AccountingPoliciesLineItems_2d261178-5695-4b6f-9c76-c71d96543697" xlink:to="loc_zi_AccountingPoliciesTable_45b89b11-0156-439f-8b42-901ff038bce8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_06f61cc5-7630-4eb9-83c3-c80e9ffe4eeb" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_zi_AccountingPoliciesTable_45b89b11-0156-439f-8b42-901ff038bce8" xlink:to="loc_srt_RangeAxis_06f61cc5-7630-4eb9-83c3-c80e9ffe4eeb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_06f61cc5-7630-4eb9-83c3-c80e9ffe4eeb_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_06f61cc5-7630-4eb9-83c3-c80e9ffe4eeb" xlink:to="loc_srt_RangeMember_06f61cc5-7630-4eb9-83c3-c80e9ffe4eeb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_303888ff-d847-45b3-b38c-5c317fa2967a" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_06f61cc5-7630-4eb9-83c3-c80e9ffe4eeb" xlink:to="loc_srt_RangeMember_303888ff-d847-45b3-b38c-5c317fa2967a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_99b6c4f4-fd38-4bd5-b1ed-66587db82166" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_303888ff-d847-45b3-b38c-5c317fa2967a" xlink:to="loc_srt_MinimumMember_99b6c4f4-fd38-4bd5-b1ed-66587db82166" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_20c1001a-4ca4-4a0c-965a-a3581738933d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_303888ff-d847-45b3-b38c-5c317fa2967a" xlink:to="loc_srt_MaximumMember_20c1001a-4ca4-4a0c-965a-a3581738933d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_2e46282c-1fe6-49af-82f7-2da3ac49ded6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_zi_AccountingPoliciesTable_45b89b11-0156-439f-8b42-901ff038bce8" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_2e46282c-1fe6-49af-82f7-2da3ac49ded6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_2e46282c-1fe6-49af-82f7-2da3ac49ded6_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_2e46282c-1fe6-49af-82f7-2da3ac49ded6" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_2e46282c-1fe6-49af-82f7-2da3ac49ded6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_1e378ca0-ec11-4f9d-8fcc-9d7d15390bb8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_2e46282c-1fe6-49af-82f7-2da3ac49ded6" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_1e378ca0-ec11-4f9d-8fcc-9d7d15390bb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_AccruedLiabilitiesCurrentMember_0f0b92a2-af96-43ad-affb-2511742b1032" xlink:href="zi-20201231.xsd#zi_AccruedLiabilitiesCurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_1e378ca0-ec11-4f9d-8fcc-9d7d15390bb8" xlink:to="loc_zi_AccruedLiabilitiesCurrentMember_0f0b92a2-af96-43ad-affb-2511742b1032" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_2c1920ed-cd83-4bff-a73f-071fda260b54" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_1e378ca0-ec11-4f9d-8fcc-9d7d15390bb8" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_2c1920ed-cd83-4bff-a73f-071fda260b54" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/RevenuefromContractswithCustomers" xlink:type="simple" xlink:href="zi-20201231.xsd#RevenuefromContractswithCustomers"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/RevenuefromContractswithCustomers" xlink:type="extended" id="i5a6bdcb21d434ad8aa7c5a2a6b7ff18e_RevenuefromContractswithCustomers"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/RevenuefromContractswithCustomersTables" xlink:type="simple" xlink:href="zi-20201231.xsd#RevenuefromContractswithCustomersTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/RevenuefromContractswithCustomersTables" xlink:type="extended" id="i382e99c9ba314e3495a0b55ad01ddd3d_RevenuefromContractswithCustomersTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/RevenuefromContractswithCustomersRevenueDisaggregatedbyServiceOfferingDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#RevenuefromContractswithCustomersRevenueDisaggregatedbyServiceOfferingDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/RevenuefromContractswithCustomersRevenueDisaggregatedbyServiceOfferingDetails" xlink:type="extended" id="i73f11167b42b49d0be5fbd7fc03b80b9_RevenuefromContractswithCustomersRevenueDisaggregatedbyServiceOfferingDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_a210cd17-5357-46bd-9a7e-aa413e7d82bc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_d2a1a538-b8e1-45fe-b4d1-dc4a8408e495" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_a210cd17-5357-46bd-9a7e-aa413e7d82bc" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_d2a1a538-b8e1-45fe-b4d1-dc4a8408e495" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_99cb93b4-b069-4bb2-a8b9-500cf3768302" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_a210cd17-5357-46bd-9a7e-aa413e7d82bc" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_99cb93b4-b069-4bb2-a8b9-500cf3768302" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_8f031d95-4b13-40ab-9588-0e45d08a0850" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_99cb93b4-b069-4bb2-a8b9-500cf3768302" xlink:to="loc_srt_ProductOrServiceAxis_8f031d95-4b13-40ab-9588-0e45d08a0850" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_8f031d95-4b13-40ab-9588-0e45d08a0850_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_8f031d95-4b13-40ab-9588-0e45d08a0850" xlink:to="loc_srt_ProductsAndServicesDomain_8f031d95-4b13-40ab-9588-0e45d08a0850_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_882203c8-5061-418b-878c-1d671ac98878" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_8f031d95-4b13-40ab-9588-0e45d08a0850" xlink:to="loc_srt_ProductsAndServicesDomain_882203c8-5061-418b-878c-1d671ac98878" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubscriptionAndCirculationMember_fdc00a23-9353-4452-904b-73e8ef6f7108" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubscriptionAndCirculationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_882203c8-5061-418b-878c-1d671ac98878" xlink:to="loc_us-gaap_SubscriptionAndCirculationMember_fdc00a23-9353-4452-904b-73e8ef6f7108" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_EmailVerificationServiceMember_7969779e-f0c3-4d72-9ca9-7808403a1ef4" xlink:href="zi-20201231.xsd#zi_EmailVerificationServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_882203c8-5061-418b-878c-1d671ac98878" xlink:to="loc_zi_EmailVerificationServiceMember_7969779e-f0c3-4d72-9ca9-7808403a1ef4" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/RevenuefromContractswithCustomersNarrativeDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#RevenuefromContractswithCustomersNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/RevenuefromContractswithCustomersNarrativeDetails" xlink:type="extended" id="i4a48d17433ea4566bd189fa4580f7fb5_RevenuefromContractswithCustomersNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_285180a8-74d5-49f5-a440-0e1c92308644" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_285180a8-74d5-49f5-a440-0e1c92308644" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_f6ce5f39-2f93-4fd5-86bf-c0a524cecd31" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_f6ce5f39-2f93-4fd5-86bf-c0a524cecd31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNetCurrent_8a753714-dcf3-4b0e-9db8-24ede9b12de5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerAssetNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_ContractWithCustomerAssetNetCurrent_8a753714-dcf3-4b0e-9db8-24ede9b12de5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_a4b36363-0e65-4532-a739-659a71dcf297" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_ContractWithCustomerLiability_a4b36363-0e65-4532-a739-659a71dcf297" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_85ef2b1f-bf42-44ee-8762-fc543c5cae55" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_85ef2b1f-bf42-44ee-8762-fc543c5cae55" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_54e87818-0dff-46b7-9178-385994da3b85" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_54e87818-0dff-46b7-9178-385994da3b85" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_ba403f5b-15bc-4267-9fce-d888cfb27c1e" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:to="loc_srt_StatementGeographicalAxis_ba403f5b-15bc-4267-9fce-d888cfb27c1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_ba403f5b-15bc-4267-9fce-d888cfb27c1e_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_ba403f5b-15bc-4267-9fce-d888cfb27c1e" xlink:to="loc_srt_SegmentGeographicalDomain_ba403f5b-15bc-4267-9fce-d888cfb27c1e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_afc185f8-eb79-43d8-b5d6-f6d550c699c3" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_ba403f5b-15bc-4267-9fce-d888cfb27c1e" xlink:to="loc_srt_SegmentGeographicalDomain_afc185f8-eb79-43d8-b5d6-f6d550c699c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_48523b04-8f40-41c5-ae65-c7fc0d6461ae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_afc185f8-eb79-43d8-b5d6-f6d550c699c3" xlink:to="loc_us-gaap_NonUsMember_48523b04-8f40-41c5-ae65-c7fc0d6461ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_25899b59-b067-4b0f-9a7d-cb25c8404cf5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_25899b59-b067-4b0f-9a7d-cb25c8404cf5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_25899b59-b067-4b0f-9a7d-cb25c8404cf5_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_25899b59-b067-4b0f-9a7d-cb25c8404cf5" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_25899b59-b067-4b0f-9a7d-cb25c8404cf5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_945329b1-be23-41da-b4ed-2aa84dbe8a3f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_25899b59-b067-4b0f-9a7d-cb25c8404cf5" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_945329b1-be23-41da-b4ed-2aa84dbe8a3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_53bf3481-e292-4ac7-9184-c05257614d7c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_945329b1-be23-41da-b4ed-2aa84dbe8a3f" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_53bf3481-e292-4ac7-9184-c05257614d7c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_3359caef-dd35-42b0-9368-2cd0df62ff38" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_3359caef-dd35-42b0-9368-2cd0df62ff38" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_3359caef-dd35-42b0-9368-2cd0df62ff38_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_3359caef-dd35-42b0-9368-2cd0df62ff38" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_3359caef-dd35-42b0-9368-2cd0df62ff38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_dd691571-a87e-46d2-b4aa-d4d76df37734" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_3359caef-dd35-42b0-9368-2cd0df62ff38" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_dd691571-a87e-46d2-b4aa-d4d76df37734" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicConcentrationRiskMember_8bae3927-ef62-4a4b-938a-f1854ea8ac6e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GeographicConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_dd691571-a87e-46d2-b4aa-d4d76df37734" xlink:to="loc_us-gaap_GeographicConcentrationRiskMember_8bae3927-ef62-4a4b-938a-f1854ea8ac6e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_f2e5cfe7-e303-4f5c-8bf9-29f5b435a2d0" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:to="loc_srt_RangeAxis_f2e5cfe7-e303-4f5c-8bf9-29f5b435a2d0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f2e5cfe7-e303-4f5c-8bf9-29f5b435a2d0_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_f2e5cfe7-e303-4f5c-8bf9-29f5b435a2d0" xlink:to="loc_srt_RangeMember_f2e5cfe7-e303-4f5c-8bf9-29f5b435a2d0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c6d652f2-0095-4559-974e-c0ccd0a1ad4d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_f2e5cfe7-e303-4f5c-8bf9-29f5b435a2d0" xlink:to="loc_srt_RangeMember_c6d652f2-0095-4559-974e-c0ccd0a1ad4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_5a28abdf-ce2f-401d-84b6-11297540793c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c6d652f2-0095-4559-974e-c0ccd0a1ad4d" xlink:to="loc_srt_MinimumMember_5a28abdf-ce2f-401d-84b6-11297540793c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_6927f3b6-5154-448c-9994-e52aed6da2e2" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c6d652f2-0095-4559-974e-c0ccd0a1ad4d" xlink:to="loc_srt_MaximumMember_6927f3b6-5154-448c-9994-e52aed6da2e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_378b8067-7eec-47f8-98b8-f81b97060174" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_378b8067-7eec-47f8-98b8-f81b97060174" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/RevenuefromContractswithCustomersNarrativeDetails_1" xlink:type="simple" xlink:href="zi-20201231.xsd#RevenuefromContractswithCustomersNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/RevenuefromContractswithCustomersNarrativeDetails_1" xlink:type="extended" id="ic19e374ab8ab43ad87f3e2d3629e2d5d_RevenuefromContractswithCustomersNarrativeDetails_1">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_285180a8-74d5-49f5-a440-0e1c92308644" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_285180a8-74d5-49f5-a440-0e1c92308644" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_f6ce5f39-2f93-4fd5-86bf-c0a524cecd31" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_f6ce5f39-2f93-4fd5-86bf-c0a524cecd31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNetCurrent_8a753714-dcf3-4b0e-9db8-24ede9b12de5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerAssetNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_ContractWithCustomerAssetNetCurrent_8a753714-dcf3-4b0e-9db8-24ede9b12de5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_a4b36363-0e65-4532-a739-659a71dcf297" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_ContractWithCustomerLiability_a4b36363-0e65-4532-a739-659a71dcf297" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_85ef2b1f-bf42-44ee-8762-fc543c5cae55" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_85ef2b1f-bf42-44ee-8762-fc543c5cae55" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_54e87818-0dff-46b7-9178-385994da3b85" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_54e87818-0dff-46b7-9178-385994da3b85" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1131729e-3160-472d-99d7-b856f43431d2" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_ba403f5b-15bc-4267-9fce-d888cfb27c1e" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:to="loc_srt_StatementGeographicalAxis_ba403f5b-15bc-4267-9fce-d888cfb27c1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_ba403f5b-15bc-4267-9fce-d888cfb27c1e_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_ba403f5b-15bc-4267-9fce-d888cfb27c1e" xlink:to="loc_srt_SegmentGeographicalDomain_ba403f5b-15bc-4267-9fce-d888cfb27c1e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_afc185f8-eb79-43d8-b5d6-f6d550c699c3" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_ba403f5b-15bc-4267-9fce-d888cfb27c1e" xlink:to="loc_srt_SegmentGeographicalDomain_afc185f8-eb79-43d8-b5d6-f6d550c699c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_48523b04-8f40-41c5-ae65-c7fc0d6461ae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_afc185f8-eb79-43d8-b5d6-f6d550c699c3" xlink:to="loc_us-gaap_NonUsMember_48523b04-8f40-41c5-ae65-c7fc0d6461ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_25899b59-b067-4b0f-9a7d-cb25c8404cf5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_25899b59-b067-4b0f-9a7d-cb25c8404cf5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_25899b59-b067-4b0f-9a7d-cb25c8404cf5_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_25899b59-b067-4b0f-9a7d-cb25c8404cf5" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_25899b59-b067-4b0f-9a7d-cb25c8404cf5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_945329b1-be23-41da-b4ed-2aa84dbe8a3f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_25899b59-b067-4b0f-9a7d-cb25c8404cf5" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_945329b1-be23-41da-b4ed-2aa84dbe8a3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_53bf3481-e292-4ac7-9184-c05257614d7c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_945329b1-be23-41da-b4ed-2aa84dbe8a3f" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_53bf3481-e292-4ac7-9184-c05257614d7c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_3359caef-dd35-42b0-9368-2cd0df62ff38" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_3359caef-dd35-42b0-9368-2cd0df62ff38" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_3359caef-dd35-42b0-9368-2cd0df62ff38_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_3359caef-dd35-42b0-9368-2cd0df62ff38" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_3359caef-dd35-42b0-9368-2cd0df62ff38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_dd691571-a87e-46d2-b4aa-d4d76df37734" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_3359caef-dd35-42b0-9368-2cd0df62ff38" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_dd691571-a87e-46d2-b4aa-d4d76df37734" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicConcentrationRiskMember_8bae3927-ef62-4a4b-938a-f1854ea8ac6e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GeographicConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_dd691571-a87e-46d2-b4aa-d4d76df37734" xlink:to="loc_us-gaap_GeographicConcentrationRiskMember_8bae3927-ef62-4a4b-938a-f1854ea8ac6e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_f2e5cfe7-e303-4f5c-8bf9-29f5b435a2d0" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_9736edd2-3221-4770-98cc-f8ad512a67da" xlink:to="loc_srt_RangeAxis_f2e5cfe7-e303-4f5c-8bf9-29f5b435a2d0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f2e5cfe7-e303-4f5c-8bf9-29f5b435a2d0_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_f2e5cfe7-e303-4f5c-8bf9-29f5b435a2d0" xlink:to="loc_srt_RangeMember_f2e5cfe7-e303-4f5c-8bf9-29f5b435a2d0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c6d652f2-0095-4559-974e-c0ccd0a1ad4d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_f2e5cfe7-e303-4f5c-8bf9-29f5b435a2d0" xlink:to="loc_srt_RangeMember_c6d652f2-0095-4559-974e-c0ccd0a1ad4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_5a28abdf-ce2f-401d-84b6-11297540793c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c6d652f2-0095-4559-974e-c0ccd0a1ad4d" xlink:to="loc_srt_MinimumMember_5a28abdf-ce2f-401d-84b6-11297540793c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_6927f3b6-5154-448c-9994-e52aed6da2e2" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c6d652f2-0095-4559-974e-c0ccd0a1ad4d" xlink:to="loc_srt_MaximumMember_6927f3b6-5154-448c-9994-e52aed6da2e2" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails" xlink:type="extended" id="i156e6150d41b43968b5da06e114505b8_RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a1055aab-20fc-46ef-9897-574c3a947b75" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_2dd93155-4822-44ac-ba67-9fc6bbbf08b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a1055aab-20fc-46ef-9897-574c3a947b75" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_2dd93155-4822-44ac-ba67-9fc6bbbf08b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_da73aa9e-4a71-48a4-b741-e2d372146337" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a1055aab-20fc-46ef-9897-574c3a947b75" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_da73aa9e-4a71-48a4-b741-e2d372146337" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_bbf0a74a-b2a3-45f8-a35b-2f87765a1d7f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a1055aab-20fc-46ef-9897-574c3a947b75" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_bbf0a74a-b2a3-45f8-a35b-2f87765a1d7f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_73ac1fe7-cde8-4bb9-9290-c74d7020d200" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_bbf0a74a-b2a3-45f8-a35b-2f87765a1d7f" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_73ac1fe7-cde8-4bb9-9290-c74d7020d200" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails_1" xlink:type="simple" xlink:href="zi-20201231.xsd#RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails_1"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails_1" xlink:type="extended" id="ided867ce328741919d9dae14ac36a959_RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails_1">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a1055aab-20fc-46ef-9897-574c3a947b75" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_2dd93155-4822-44ac-ba67-9fc6bbbf08b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a1055aab-20fc-46ef-9897-574c3a947b75" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_2dd93155-4822-44ac-ba67-9fc6bbbf08b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_da73aa9e-4a71-48a4-b741-e2d372146337" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a1055aab-20fc-46ef-9897-574c3a947b75" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_da73aa9e-4a71-48a4-b741-e2d372146337" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_bbf0a74a-b2a3-45f8-a35b-2f87765a1d7f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a1055aab-20fc-46ef-9897-574c3a947b75" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_bbf0a74a-b2a3-45f8-a35b-2f87765a1d7f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/BusinessCombinations" xlink:type="simple" xlink:href="zi-20201231.xsd#BusinessCombinations"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/BusinessCombinations" xlink:type="extended" id="ibc3e4a7edc98464c814bea9d4d0ac615_BusinessCombinations"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/BusinessCombinationsTables" xlink:type="simple" xlink:href="zi-20201231.xsd#BusinessCombinationsTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/BusinessCombinationsTables" xlink:type="extended" id="i77de9456b3474d308961eb9c089d0e59_BusinessCombinationsTables">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_961cf2c1-87d3-4d90-8c18-ac0c513c3b41" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTextBlock_01c9d1af-7637-4d3d-bc95-8bd2f22e52f0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_961cf2c1-87d3-4d90-8c18-ac0c513c3b41" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTextBlock_01c9d1af-7637-4d3d-bc95-8bd2f22e52f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_d1e1c9cf-67b9-42cd-9c6c-3c39afa4c0f4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_961cf2c1-87d3-4d90-8c18-ac0c513c3b41" xlink:to="loc_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_d1e1c9cf-67b9-42cd-9c6c-3c39afa4c0f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock_17b393f6-3b40-44c6-adc2-0f720034c01b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_961cf2c1-87d3-4d90-8c18-ac0c513c3b41" xlink:to="loc_us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock_17b393f6-3b40-44c6-adc2-0f720034c01b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaInformationTextBlock_cb3259e3-d218-46f3-8e43-deebbf304521" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_961cf2c1-87d3-4d90-8c18-ac0c513c3b41" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaInformationTextBlock_cb3259e3-d218-46f3-8e43-deebbf304521" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_818e73d5-f6fd-49c5-9215-dc72bb270fbd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_961cf2c1-87d3-4d90-8c18-ac0c513c3b41" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_818e73d5-f6fd-49c5-9215-dc72bb270fbd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_fb52e14c-c5bd-47cb-aad7-892a6ea354d9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_818e73d5-f6fd-49c5-9215-dc72bb270fbd" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_fb52e14c-c5bd-47cb-aad7-892a6ea354d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fb52e14c-c5bd-47cb-aad7-892a6ea354d9_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_fb52e14c-c5bd-47cb-aad7-892a6ea354d9" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fb52e14c-c5bd-47cb-aad7-892a6ea354d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4ea5a5a1-9dcc-4002-9974-bdb2233bada7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_fb52e14c-c5bd-47cb-aad7-892a6ea354d9" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4ea5a5a1-9dcc-4002-9974-bdb2233bada7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_KomikoLTDMember_bb876a5a-9506-4b11-a416-bb2fc073ace7" xlink:href="zi-20201231.xsd#zi_KomikoLTDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4ea5a5a1-9dcc-4002-9974-bdb2233bada7" xlink:to="loc_zi_KomikoLTDMember_bb876a5a-9506-4b11-a416-bb2fc073ace7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreAcquisitionZoomInformationIncMember_6c99e464-f6cc-46ea-89da-f7ce7bdb8154" xlink:href="zi-20201231.xsd#zi_PreAcquisitionZoomInformationIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4ea5a5a1-9dcc-4002-9974-bdb2233bada7" xlink:to="loc_zi_PreAcquisitionZoomInformationIncMember_6c99e464-f6cc-46ea-89da-f7ce7bdb8154" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/BusinessCombinationsNarrativeDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#BusinessCombinationsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/BusinessCombinationsNarrativeDetails" xlink:type="extended" id="i45c8e009964c40d98bb4a0599663fb69_BusinessCombinationsNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfBusinessesAcquired_403eb53a-0fe4-4b52-ab77-a42037831791" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfBusinessesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_NumberOfBusinessesAcquired_403eb53a-0fe4-4b52-ab77-a42037831791" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_a0acd8c2-dc78-41c6-bd40-fa88a9574a17" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_a0acd8c2-dc78-41c6-bd40-fa88a9574a17" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_dd27fa84-92ca-4337-a86a-d3a69498b689" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_dd27fa84-92ca-4337-a86a-d3a69498b689" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationConsiderationTransferredIncentiveCompensation_843b10bc-58c1-49a9-a115-9f135313cee9" xlink:href="zi-20201231.xsd#zi_BusinessCombinationConsiderationTransferredIncentiveCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_zi_BusinessCombinationConsiderationTransferredIncentiveCompensation_843b10bc-58c1-49a9-a115-9f135313cee9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_ee1f9153-8067-4da8-9a6a-a728c747d132" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_ee1f9153-8067-4da8-9a6a-a728c747d132" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationContingentConsiderationArrangementsPercentageOfContingentPaymentsAttributableToPurchaseConsideration_6f71df2b-f3b8-4887-8f4a-c68f669934fc" xlink:href="zi-20201231.xsd#zi_BusinessCombinationContingentConsiderationArrangementsPercentageOfContingentPaymentsAttributableToPurchaseConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_zi_BusinessCombinationContingentConsiderationArrangementsPercentageOfContingentPaymentsAttributableToPurchaseConsideration_6f71df2b-f3b8-4887-8f4a-c68f669934fc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInTheRangeOfOutcomesContingentConsiderationLiabilityValueHigh_33a3d114-848e-4e20-b80d-4d31d9faf301" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInTheRangeOfOutcomesContingentConsiderationLiabilityValueHigh"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInTheRangeOfOutcomesContingentConsiderationLiabilityValueHigh_33a3d114-848e-4e20-b80d-4d31d9faf301" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_cf8825f1-4183-47df-a1fb-bff9296b6594" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_cf8825f1-4183-47df-a1fb-bff9296b6594" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_b9e7846a-5e5c-4a28-9ee5-e0fba12c778a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_b9e7846a-5e5c-4a28-9ee5-e0fba12c778a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_6a015d21-2723-4e31-83c8-87261e09f096" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_6a015d21-2723-4e31-83c8-87261e09f096" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_NumberOfCustomersServed_368db44d-144c-48c0-9109-30d088ea4532" xlink:href="zi-20201231.xsd#zi_NumberOfCustomersServed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_zi_NumberOfCustomersServed_368db44d-144c-48c0-9109-30d088ea4532" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_cab4608b-c8f2-4c8a-8fb8-4813dba81908" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_cab4608b-c8f2-4c8a-8fb8-4813dba81908" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAcquiredFromAcquisition_b11aa039-1247-42f3-88fa-2b406482085d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAcquiredFromAcquisition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_CashAcquiredFromAcquisition_b11aa039-1247-42f3-88fa-2b406482085d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationDeferredConsiderationCurrent_5bd443ff-666a-42e5-9185-00bfe3bc8819" xlink:href="zi-20201231.xsd#zi_BusinessCombinationDeferredConsiderationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_zi_BusinessCombinationDeferredConsiderationCurrent_5bd443ff-666a-42e5-9185-00bfe3bc8819" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationDeferredConsiderationNoncurrent_71ace137-ea2e-48cf-941e-db33a46fc594" xlink:href="zi-20201231.xsd#zi_BusinessCombinationDeferredConsiderationNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_zi_BusinessCombinationDeferredConsiderationNoncurrent_71ace137-ea2e-48cf-941e-db33a46fc594" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_db0f9d6d-d802-4bac-9dc1-b9a639f3e23d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_db0f9d6d-d802-4bac-9dc1-b9a639f3e23d" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_99933b9d-5ac2-458e-8b06-1ff495b90dcd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_ContractWithCustomerLiability_99933b9d-5ac2-458e-8b06-1ff495b90dcd" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredRevenue_74a94d6a-661e-4faf-bce5-def352356e9b" xlink:href="zi-20201231.xsd#zi_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_zi_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredRevenue_74a94d6a-661e-4faf-bce5-def352356e9b" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationUnearnedRevenueRecognitionPeriod_19c8e4a3-e58a-495c-be76-2a6996ae91b7" xlink:href="zi-20201231.xsd#zi_BusinessCombinationUnearnedRevenueRecognitionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_zi_BusinessCombinationUnearnedRevenueRecognitionPeriod_19c8e4a3-e58a-495c-be76-2a6996ae91b7" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationContingentConsiderationPotentialFuturePayments_a1b19746-fdcb-4012-b0f8-7daada95f168" xlink:href="zi-20201231.xsd#zi_BusinessCombinationContingentConsiderationPotentialFuturePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_zi_BusinessCombinationContingentConsiderationPotentialFuturePayments_a1b19746-fdcb-4012-b0f8-7daada95f168" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationContingentConsiderationExpense_a40d6818-998f-4e2c-9e21-76808db7ae38" xlink:href="zi-20201231.xsd#zi_BusinessCombinationContingentConsiderationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_zi_BusinessCombinationContingentConsiderationExpense_a40d6818-998f-4e2c-9e21-76808db7ae38" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessAcquisitionProFormaTransactionCostsAndBonuses_b1c1580f-d463-462f-a908-f4360557cbe0" xlink:href="zi-20201231.xsd#zi_BusinessAcquisitionProFormaTransactionCostsAndBonuses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_zi_BusinessAcquisitionProFormaTransactionCostsAndBonuses_b1c1580f-d463-462f-a908-f4360557cbe0" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_7f0aadd5-af85-4f0f-bc1b-2c6dee642ed1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_7f0aadd5-af85-4f0f-bc1b-2c6dee642ed1" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2f8aeb65-0436-4d53-94e4-8af3e6accaf5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70a582c0-8d71-4cbb-9ab4-b145f1a7177c" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2f8aeb65-0436-4d53-94e4-8af3e6accaf5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_e56c96f2-71f6-4a28-a83e-af6c3cbf353d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2f8aeb65-0436-4d53-94e4-8af3e6accaf5" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_e56c96f2-71f6-4a28-a83e-af6c3cbf353d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e56c96f2-71f6-4a28-a83e-af6c3cbf353d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e56c96f2-71f6-4a28-a83e-af6c3cbf353d" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e56c96f2-71f6-4a28-a83e-af6c3cbf353d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9e5812cf-1188-4906-8e06-e224a07e992e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e56c96f2-71f6-4a28-a83e-af6c3cbf353d" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9e5812cf-1188-4906-8e06-e224a07e992e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_A2020BusinessAcquisitionsMember_07e316df-0717-43de-b858-d9c4ef47a42c" xlink:href="zi-20201231.xsd#zi_A2020BusinessAcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9e5812cf-1188-4906-8e06-e224a07e992e" xlink:to="loc_zi_A2020BusinessAcquisitionsMember_07e316df-0717-43de-b858-d9c4ef47a42c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_KomikoLTDMember_9e1ca9f8-577b-482b-bdc5-25f6f2aecde2" xlink:href="zi-20201231.xsd#zi_KomikoLTDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9e5812cf-1188-4906-8e06-e224a07e992e" xlink:to="loc_zi_KomikoLTDMember_9e1ca9f8-577b-482b-bdc5-25f6f2aecde2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreAcquisitionZoomInformationIncMember_b7bc5e26-e310-403e-99d4-6f91748d6051" xlink:href="zi-20201231.xsd#zi_PreAcquisitionZoomInformationIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9e5812cf-1188-4906-8e06-e224a07e992e" xlink:to="loc_zi_PreAcquisitionZoomInformationIncMember_b7bc5e26-e310-403e-99d4-6f91748d6051" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_43ab1c7d-7105-4bcf-8086-72c3bd56f114" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2f8aeb65-0436-4d53-94e4-8af3e6accaf5" xlink:to="loc_us-gaap_AwardTypeAxis_43ab1c7d-7105-4bcf-8086-72c3bd56f114" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_43ab1c7d-7105-4bcf-8086-72c3bd56f114_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_43ab1c7d-7105-4bcf-8086-72c3bd56f114" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_43ab1c7d-7105-4bcf-8086-72c3bd56f114_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_df6f53f2-9f55-4e22-96ac-76b2d83668a9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_43ab1c7d-7105-4bcf-8086-72c3bd56f114" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_df6f53f2-9f55-4e22-96ac-76b2d83668a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_6bf6de9f-57d8-472f-9759-b3cbac7a87a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_df6f53f2-9f55-4e22-96ac-76b2d83668a9" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_6bf6de9f-57d8-472f-9759-b3cbac7a87a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b7be42de-e48d-410c-a5bc-d1658207a258" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2f8aeb65-0436-4d53-94e4-8af3e6accaf5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b7be42de-e48d-410c-a5bc-d1658207a258" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b7be42de-e48d-410c-a5bc-d1658207a258_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b7be42de-e48d-410c-a5bc-d1658207a258" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b7be42de-e48d-410c-a5bc-d1658207a258_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c4fd9e74-c1c4-4943-87c2-8dc6c2fdc4ad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b7be42de-e48d-410c-a5bc-d1658207a258" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c4fd9e74-c1c4-4943-87c2-8dc6c2fdc4ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_61f4723f-8d79-4e90-87bd-fa5141b165e9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c4fd9e74-c1c4-4943-87c2-8dc6c2fdc4ad" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_61f4723f-8d79-4e90-87bd-fa5141b165e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_f0153e20-7c6f-4ecb-b27a-5b89d2f43a51" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2f8aeb65-0436-4d53-94e4-8af3e6accaf5" xlink:to="loc_srt_StatementScenarioAxis_f0153e20-7c6f-4ecb-b27a-5b89d2f43a51" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_f0153e20-7c6f-4ecb-b27a-5b89d2f43a51_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_f0153e20-7c6f-4ecb-b27a-5b89d2f43a51" xlink:to="loc_srt_ScenarioUnspecifiedDomain_f0153e20-7c6f-4ecb-b27a-5b89d2f43a51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_77ddaad7-54f8-401d-8fca-3142822a6d60" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_f0153e20-7c6f-4ecb-b27a-5b89d2f43a51" xlink:to="loc_srt_ScenarioUnspecifiedDomain_77ddaad7-54f8-401d-8fca-3142822a6d60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_72a6487a-5be0-443a-a7ac-10622a27fb4f" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_77ddaad7-54f8-401d-8fca-3142822a6d60" xlink:to="loc_srt_ScenarioForecastMember_72a6487a-5be0-443a-a7ac-10622a27fb4f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContingentConsiderationByTypeAxis_1ccd5747-7d00-467e-9339-4d327ea48944" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContingentConsiderationByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2f8aeb65-0436-4d53-94e4-8af3e6accaf5" xlink:to="loc_us-gaap_ContingentConsiderationByTypeAxis_1ccd5747-7d00-467e-9339-4d327ea48944" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContingentConsiderationTypeDomain_1ccd5747-7d00-467e-9339-4d327ea48944_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContingentConsiderationTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContingentConsiderationByTypeAxis_1ccd5747-7d00-467e-9339-4d327ea48944" xlink:to="loc_us-gaap_ContingentConsiderationTypeDomain_1ccd5747-7d00-467e-9339-4d327ea48944_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContingentConsiderationTypeDomain_dd6db3d8-be86-4076-a010-bdc109934bc1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContingentConsiderationTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContingentConsiderationByTypeAxis_1ccd5747-7d00-467e-9339-4d327ea48944" xlink:to="loc_us-gaap_ContingentConsiderationTypeDomain_dd6db3d8-be86-4076-a010-bdc109934bc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_CashVestingPaymentProgramMember_bb0b3690-4829-44d8-92bd-bc529b514a57" xlink:href="zi-20201231.xsd#zi_CashVestingPaymentProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContingentConsiderationTypeDomain_dd6db3d8-be86-4076-a010-bdc109934bc1" xlink:to="loc_zi_CashVestingPaymentProgramMember_bb0b3690-4829-44d8-92bd-bc529b514a57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_66bdc723-4f8a-48b3-be80-e11c7bfc3ded" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2f8aeb65-0436-4d53-94e4-8af3e6accaf5" xlink:to="loc_dei_LegalEntityAxis_66bdc723-4f8a-48b3-be80-e11c7bfc3ded" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_66bdc723-4f8a-48b3-be80-e11c7bfc3ded_default" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_66bdc723-4f8a-48b3-be80-e11c7bfc3ded" xlink:to="loc_dei_EntityDomain_66bdc723-4f8a-48b3-be80-e11c7bfc3ded_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_bc8d070e-0453-4c3f-9f38-e6ff24cb332c" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_66bdc723-4f8a-48b3-be80-e11c7bfc3ded" xlink:to="loc_dei_EntityDomain_bc8d070e-0453-4c3f-9f38-e6ff24cb332c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreAcquisitionZoomInformationIncMember_472223d0-7b15-442d-8ed4-b21d5e890f80" xlink:href="zi-20201231.xsd#zi_PreAcquisitionZoomInformationIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_bc8d070e-0453-4c3f-9f38-e6ff24cb332c" xlink:to="loc_zi_PreAcquisitionZoomInformationIncMember_472223d0-7b15-442d-8ed4-b21d5e890f80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_2cac677b-1cb5-4dcb-8ef1-5f6ace867fee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2f8aeb65-0436-4d53-94e4-8af3e6accaf5" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_2cac677b-1cb5-4dcb-8ef1-5f6ace867fee" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_2cac677b-1cb5-4dcb-8ef1-5f6ace867fee_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_2cac677b-1cb5-4dcb-8ef1-5f6ace867fee" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_2cac677b-1cb5-4dcb-8ef1-5f6ace867fee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_669d297b-16b3-40ea-a839-7cf964aaf62d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_2cac677b-1cb5-4dcb-8ef1-5f6ace867fee" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_669d297b-16b3-40ea-a839-7cf964aaf62d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesMember_9a1171c6-1ddc-4587-bc63-81efaa7e16b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_669d297b-16b3-40ea-a839-7cf964aaf62d" xlink:to="loc_us-gaap_AccruedLiabilitiesMember_9a1171c6-1ddc-4587-bc63-81efaa7e16b7" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/BusinessCombinationsAcquisitionDateFairValueofConsiderationTransferredDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#BusinessCombinationsAcquisitionDateFairValueofConsiderationTransferredDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/BusinessCombinationsAcquisitionDateFairValueofConsiderationTransferredDetails" xlink:type="extended" id="i48b214aa18f04c748475f333b2c31bc9_BusinessCombinationsAcquisitionDateFairValueofConsiderationTransferredDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_d2f3d8ad-6c50-48dd-8876-b2641dcf413d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_cca941c1-c2a0-4038-98c7-af901d7a5fc6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d2f3d8ad-6c50-48dd-8876-b2641dcf413d" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_cca941c1-c2a0-4038-98c7-af901d7a5fc6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred_47c139df-e51a-42a2-bbc2-85c904eec3f2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d2f3d8ad-6c50-48dd-8876-b2641dcf413d" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred_47c139df-e51a-42a2-bbc2-85c904eec3f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_2b8fc766-191d-4811-aa87-44626f28ac18" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d2f3d8ad-6c50-48dd-8876-b2641dcf413d" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_2b8fc766-191d-4811-aa87-44626f28ac18" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_29db70d7-dc0d-4fc1-9f50-3c00a7485577" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d2f3d8ad-6c50-48dd-8876-b2641dcf413d" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_29db70d7-dc0d-4fc1-9f50-3c00a7485577" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationContingentEarnOutPayments_6b7d4b81-df33-4913-8b72-64c262605c55" xlink:href="zi-20201231.xsd#zi_BusinessCombinationContingentEarnOutPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d2f3d8ad-6c50-48dd-8876-b2641dcf413d" xlink:to="loc_zi_BusinessCombinationContingentEarnOutPayments_6b7d4b81-df33-4913-8b72-64c262605c55" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationLiabilityIncurredForEquityAwardSettlement_69c28781-0468-45df-8455-632f1a19cc71" xlink:href="zi-20201231.xsd#zi_BusinessCombinationLiabilityIncurredForEquityAwardSettlement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d2f3d8ad-6c50-48dd-8876-b2641dcf413d" xlink:to="loc_zi_BusinessCombinationLiabilityIncurredForEquityAwardSettlement_69c28781-0468-45df-8455-632f1a19cc71" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationPortionOfReplacementAwardsAttributableToPreAcquisitionService_d3c3d642-f097-4df1-b30e-5b9c6872d189" xlink:href="zi-20201231.xsd#zi_BusinessCombinationPortionOfReplacementAwardsAttributableToPreAcquisitionService"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d2f3d8ad-6c50-48dd-8876-b2641dcf413d" xlink:to="loc_zi_BusinessCombinationPortionOfReplacementAwardsAttributableToPreAcquisitionService_d3c3d642-f097-4df1-b30e-5b9c6872d189" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationPurchaseConsiderationLiabilitiesOther_bb6c5f94-d97a-4fe2-b01f-cbcb2cdbc2c3" xlink:href="zi-20201231.xsd#zi_BusinessCombinationPurchaseConsiderationLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d2f3d8ad-6c50-48dd-8876-b2641dcf413d" xlink:to="loc_zi_BusinessCombinationPurchaseConsiderationLiabilitiesOther_bb6c5f94-d97a-4fe2-b01f-cbcb2cdbc2c3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_f976a15c-75bd-45fb-8373-1e5cbb77590e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d2f3d8ad-6c50-48dd-8876-b2641dcf413d" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_f976a15c-75bd-45fb-8373-1e5cbb77590e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ba0131bc-041b-455b-9339-050c0bd86b06" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d2f3d8ad-6c50-48dd-8876-b2641dcf413d" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ba0131bc-041b-455b-9339-050c0bd86b06" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_6b41bd77-0d6e-449a-94ce-c1f493244884" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ba0131bc-041b-455b-9339-050c0bd86b06" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_6b41bd77-0d6e-449a-94ce-c1f493244884" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6b41bd77-0d6e-449a-94ce-c1f493244884_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6b41bd77-0d6e-449a-94ce-c1f493244884" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6b41bd77-0d6e-449a-94ce-c1f493244884_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ee895b4b-d03d-41e3-b1e4-288d58d7f4c4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6b41bd77-0d6e-449a-94ce-c1f493244884" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ee895b4b-d03d-41e3-b1e4-288d58d7f4c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_A2020BusinessAcquisitionsMember_5738276a-a7a9-47a7-a0fc-2243f87ef842" xlink:href="zi-20201231.xsd#zi_A2020BusinessAcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ee895b4b-d03d-41e3-b1e4-288d58d7f4c4" xlink:to="loc_zi_A2020BusinessAcquisitionsMember_5738276a-a7a9-47a7-a0fc-2243f87ef842" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_KomikoLTDMember_be095c63-f1ac-4c99-850e-73180647f2ed" xlink:href="zi-20201231.xsd#zi_KomikoLTDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ee895b4b-d03d-41e3-b1e4-288d58d7f4c4" xlink:to="loc_zi_KomikoLTDMember_be095c63-f1ac-4c99-850e-73180647f2ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreAcquisitionZoomInformationIncMember_3b399496-0d80-430a-9513-b0de659b2a9f" xlink:href="zi-20201231.xsd#zi_PreAcquisitionZoomInformationIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ee895b4b-d03d-41e3-b1e4-288d58d7f4c4" xlink:to="loc_zi_PreAcquisitionZoomInformationIncMember_3b399496-0d80-430a-9513-b0de659b2a9f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_40b68ff5-fac7-4aeb-8013-2d1b218aeee1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ba0131bc-041b-455b-9339-050c0bd86b06" xlink:to="loc_us-gaap_StatementClassOfStockAxis_40b68ff5-fac7-4aeb-8013-2d1b218aeee1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_40b68ff5-fac7-4aeb-8013-2d1b218aeee1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_40b68ff5-fac7-4aeb-8013-2d1b218aeee1" xlink:to="loc_us-gaap_ClassOfStockDomain_40b68ff5-fac7-4aeb-8013-2d1b218aeee1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_89f92e2b-500b-45e5-bdfe-6dda979bc56a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_40b68ff5-fac7-4aeb-8013-2d1b218aeee1" xlink:to="loc_us-gaap_ClassOfStockDomain_89f92e2b-500b-45e5-bdfe-6dda979bc56a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_c17ceca2-d3a2-44c3-86b5-9931f9c61109" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_89f92e2b-500b-45e5-bdfe-6dda979bc56a" xlink:to="loc_us-gaap_CommonClassAMember_c17ceca2-d3a2-44c3-86b5-9931f9c61109" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/BusinessCombinationsFairValuesofAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#BusinessCombinationsFairValuesofAssetsAcquiredandLiabilitiesAssumedDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/BusinessCombinationsFairValuesofAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="extended" id="i09bda5689e844f2781ea7b6b6054c664_BusinessCombinationsFairValuesofAssetsAcquiredandLiabilitiesAssumedDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_d3141e6f-f021-47a9-991d-41034e298c25" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_d3141e6f-f021-47a9-991d-41034e298c25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_4929388d-e1a2-49a6-8263-eb066a0280bf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_4929388d-e1a2-49a6-8263-eb066a0280bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_6c3770a8-7bc9-493b-8e46-9fc4afba9a5d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_6c3770a8-7bc9-493b-8e46-9fc4afba9a5d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_16288a04-3e18-4bed-8023-2c9ca9a7c965" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_16288a04-3e18-4bed-8023-2c9ca9a7c965" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAssets_1716b74f-6055-41e9-9c5f-4625dd06662b" xlink:href="zi-20201231.xsd#zi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_zi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAssets_1716b74f-6055-41e9-9c5f-4625dd06662b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_ae15b997-0a76-4e0f-bb6a-ee4e4848d544" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_ae15b997-0a76-4e0f-bb6a-ee4e4848d544" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_530d9945-28e8-43e7-b041-9f6fbd755cea" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_530d9945-28e8-43e7-b041-9f6fbd755cea" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_62d7a699-7d96-4966-8671-4b021d4c8aea" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_62d7a699-7d96-4966-8671-4b021d4c8aea" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_670f93c2-e8c0-4707-b121-4798318f42e1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_670f93c2-e8c0-4707-b121-4798318f42e1" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation_58cefb2a-7f4e-49f7-850c-47af06316369" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation_58cefb2a-7f4e-49f7-850c-47af06316369" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_fccb4773-56e4-414c-84cf-9db02cd85f7d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_fccb4773-56e4-414c-84cf-9db02cd85f7d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_53710ad2-2d44-40fa-a51c-be9149ab03df" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_53710ad2-2d44-40fa-a51c-be9149ab03df" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_ea5470b9-66e7-41e7-b18c-783f8342f0b6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_Goodwill_ea5470b9-66e7-41e7-b18c-783f8342f0b6" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_382afc57-af21-4882-beb3-8f876232ce48" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_382afc57-af21-4882-beb3-8f876232ce48" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_7070eb91-3a40-44fa-b5cc-f0c9919234b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_7070eb91-3a40-44fa-b5cc-f0c9919234b7" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_99ffe459-4691-49c8-88a3-e251cfcf4afb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_99ffe459-4691-49c8-88a3-e251cfcf4afb" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationDeferredConsideration_df491bd8-f7d8-43d2-b385-f7a955aa24c5" xlink:href="zi-20201231.xsd#zi_BusinessCombinationDeferredConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_zi_BusinessCombinationDeferredConsideration_df491bd8-f7d8-43d2-b385-f7a955aa24c5" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAcquiredFromAcquisition_ff60ba04-3074-4118-a530-6fcd02537479" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAcquiredFromAcquisition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_CashAcquiredFromAcquisition_ff60ba04-3074-4118-a530-6fcd02537479" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessCombinationContingentEarnOutPayments_0370a3fc-4de4-4cde-a460-75747e28bdc7" xlink:href="zi-20201231.xsd#zi_BusinessCombinationContingentEarnOutPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_zi_BusinessCombinationContingentEarnOutPayments_0370a3fc-4de4-4cde-a460-75747e28bdc7" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_b852339f-a807-43ca-9497-6f210a280de7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_b852339f-a807-43ca-9497-6f210a280de7" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_591bab0e-6156-4a42-9084-ed0cf5d0dac1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_52b8dffa-2ac7-483d-8010-cb42d89f9204" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_591bab0e-6156-4a42-9084-ed0cf5d0dac1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_6e05c11b-95a4-4069-9635-6f490fa73eb8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_591bab0e-6156-4a42-9084-ed0cf5d0dac1" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_6e05c11b-95a4-4069-9635-6f490fa73eb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6e05c11b-95a4-4069-9635-6f490fa73eb8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6e05c11b-95a4-4069-9635-6f490fa73eb8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6e05c11b-95a4-4069-9635-6f490fa73eb8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_69d57200-4b1f-4f0c-b196-e908425a0932" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6e05c11b-95a4-4069-9635-6f490fa73eb8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_69d57200-4b1f-4f0c-b196-e908425a0932" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_KomikoLTDMember_7b4ff8f1-88e8-4f8f-853c-6711a671132e" xlink:href="zi-20201231.xsd#zi_KomikoLTDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_69d57200-4b1f-4f0c-b196-e908425a0932" xlink:to="loc_zi_KomikoLTDMember_7b4ff8f1-88e8-4f8f-853c-6711a671132e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreAcquisitionZoomInformationIncMember_2849e0c8-2915-4c5d-ad29-359153d575ce" xlink:href="zi-20201231.xsd#zi_PreAcquisitionZoomInformationIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_69d57200-4b1f-4f0c-b196-e908425a0932" xlink:to="loc_zi_PreAcquisitionZoomInformationIncMember_2849e0c8-2915-4c5d-ad29-359153d575ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_A2020BusinessAcquisitionsMember_7b688252-78ea-40e5-bf60-54caef4106e5" xlink:href="zi-20201231.xsd#zi_A2020BusinessAcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_69d57200-4b1f-4f0c-b196-e908425a0932" xlink:to="loc_zi_A2020BusinessAcquisitionsMember_7b688252-78ea-40e5-bf60-54caef4106e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e555dd89-e953-4157-a501-6b050fa919ba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_591bab0e-6156-4a42-9084-ed0cf5d0dac1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e555dd89-e953-4157-a501-6b050fa919ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e555dd89-e953-4157-a501-6b050fa919ba_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e555dd89-e953-4157-a501-6b050fa919ba" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e555dd89-e953-4157-a501-6b050fa919ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_84cdc790-2eff-4ae1-bc76-5460ef4b98c8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e555dd89-e953-4157-a501-6b050fa919ba" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_84cdc790-2eff-4ae1-bc76-5460ef4b98c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_2b49bb26-bb9c-458f-a04d-8779ea23738c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_84cdc790-2eff-4ae1-bc76-5460ef4b98c8" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_2b49bb26-bb9c-458f-a04d-8779ea23738c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_e5496ebf-7f9e-4258-86f1-3d363c364c5f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_591bab0e-6156-4a42-9084-ed0cf5d0dac1" xlink:to="loc_us-gaap_StatementClassOfStockAxis_e5496ebf-7f9e-4258-86f1-3d363c364c5f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_e5496ebf-7f9e-4258-86f1-3d363c364c5f_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_e5496ebf-7f9e-4258-86f1-3d363c364c5f" xlink:to="loc_us-gaap_ClassOfStockDomain_e5496ebf-7f9e-4258-86f1-3d363c364c5f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_581ba708-d8a9-4f34-a076-a1702b135a3b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_e5496ebf-7f9e-4258-86f1-3d363c364c5f" xlink:to="loc_us-gaap_ClassOfStockDomain_581ba708-d8a9-4f34-a076-a1702b135a3b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_5ecbb506-f2d6-4301-9e28-d5c6a23e52aa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_581ba708-d8a9-4f34-a076-a1702b135a3b" xlink:to="loc_us-gaap_CommonClassAMember_5ecbb506-f2d6-4301-9e28-d5c6a23e52aa" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/BusinessCombinationsComponentsofIdentifiableIntangibleAssetsAcquiredDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#BusinessCombinationsComponentsofIdentifiableIntangibleAssetsAcquiredDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/BusinessCombinationsComponentsofIdentifiableIntangibleAssetsAcquiredDetails" xlink:type="extended" id="ic93c7deab4db4970a141bc1c4b083a0a_BusinessCombinationsComponentsofIdentifiableIntangibleAssetsAcquiredDetails">
    <link:loc xlink:type="locator" xlink:label="loc_zi_ScheduleOfAcquiredAssetsByMajorClassLineItems_78025305-ed1e-4629-9273-dc611d09e6b3" xlink:href="zi-20201231.xsd#zi_ScheduleOfAcquiredAssetsByMajorClassLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefinitelivedIntangibleAssetsAcquired_ae607df5-02b5-478d-89de-d096f5020c87" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefinitelivedIntangibleAssetsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_ScheduleOfAcquiredAssetsByMajorClassLineItems_78025305-ed1e-4629-9273-dc611d09e6b3" xlink:to="loc_us-gaap_IndefinitelivedIntangibleAssetsAcquired_ae607df5-02b5-478d-89de-d096f5020c87" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_92af960d-4eee-45a1-a173-cb1af4fbd62a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_ScheduleOfAcquiredAssetsByMajorClassLineItems_78025305-ed1e-4629-9273-dc611d09e6b3" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_92af960d-4eee-45a1-a173-cb1af4fbd62a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_FiniteAndIndefiniteLivedIntangibleAssetsAcquired_4990acef-2b6a-43a3-a8eb-5cb3ca6448c3" xlink:href="zi-20201231.xsd#zi_FiniteAndIndefiniteLivedIntangibleAssetsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_ScheduleOfAcquiredAssetsByMajorClassLineItems_78025305-ed1e-4629-9273-dc611d09e6b3" xlink:to="loc_zi_FiniteAndIndefiniteLivedIntangibleAssetsAcquired_4990acef-2b6a-43a3-a8eb-5cb3ca6448c3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_a23bf4fa-c7f1-416e-b1f7-893bfa2ee6d4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_zi_ScheduleOfAcquiredAssetsByMajorClassLineItems_78025305-ed1e-4629-9273-dc611d09e6b3" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_a23bf4fa-c7f1-416e-b1f7-893bfa2ee6d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ScheduleOfAcquiredAssetsByMajorClassTable_12c92820-e02e-4209-9327-8f7cb56297b4" xlink:href="zi-20201231.xsd#zi_ScheduleOfAcquiredAssetsByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_zi_ScheduleOfAcquiredAssetsByMajorClassLineItems_78025305-ed1e-4629-9273-dc611d09e6b3" xlink:to="loc_zi_ScheduleOfAcquiredAssetsByMajorClassTable_12c92820-e02e-4209-9327-8f7cb56297b4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_018891e9-0963-475d-b402-c73bdf6d0a23" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_zi_ScheduleOfAcquiredAssetsByMajorClassTable_12c92820-e02e-4209-9327-8f7cb56297b4" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_018891e9-0963-475d-b402-c73bdf6d0a23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_018891e9-0963-475d-b402-c73bdf6d0a23_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_018891e9-0963-475d-b402-c73bdf6d0a23" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_018891e9-0963-475d-b402-c73bdf6d0a23_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_94626d92-1df3-400e-855d-58cf52e8d17e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_018891e9-0963-475d-b402-c73bdf6d0a23" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_94626d92-1df3-400e-855d-58cf52e8d17e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreAcquisitionZoomInformationIncMember_5c2ed2e1-21b2-4991-beeb-777026d845e1" xlink:href="zi-20201231.xsd#zi_PreAcquisitionZoomInformationIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_94626d92-1df3-400e-855d-58cf52e8d17e" xlink:to="loc_zi_PreAcquisitionZoomInformationIncMember_5c2ed2e1-21b2-4991-beeb-777026d845e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_A2020BusinessAcquisitionsMember_8cafe7b4-179a-40fc-9f3d-9ee124307fae" xlink:href="zi-20201231.xsd#zi_A2020BusinessAcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_94626d92-1df3-400e-855d-58cf52e8d17e" xlink:to="loc_zi_A2020BusinessAcquisitionsMember_8cafe7b4-179a-40fc-9f3d-9ee124307fae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_3b93d057-17a3-4fb6-9b23-ad6eeba97c9a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_zi_ScheduleOfAcquiredAssetsByMajorClassTable_12c92820-e02e-4209-9327-8f7cb56297b4" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_3b93d057-17a3-4fb6-9b23-ad6eeba97c9a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_3b93d057-17a3-4fb6-9b23-ad6eeba97c9a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_3b93d057-17a3-4fb6-9b23-ad6eeba97c9a" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_3b93d057-17a3-4fb6-9b23-ad6eeba97c9a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_35984135-ce36-4edc-936b-e6a9b97dab04" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_3b93d057-17a3-4fb6-9b23-ad6eeba97c9a" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_35984135-ce36-4edc-936b-e6a9b97dab04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BrandPortfolioMember_d5b6f94b-51be-4a33-b7b3-836a76d2e52d" xlink:href="zi-20201231.xsd#zi_BrandPortfolioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_35984135-ce36-4edc-936b-e6a9b97dab04" xlink:to="loc_zi_BrandPortfolioMember_d5b6f94b-51be-4a33-b7b3-836a76d2e52d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e269bbc9-4f8c-4043-b484-d3bfdf4c2536" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_zi_ScheduleOfAcquiredAssetsByMajorClassTable_12c92820-e02e-4209-9327-8f7cb56297b4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e269bbc9-4f8c-4043-b484-d3bfdf4c2536" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e269bbc9-4f8c-4043-b484-d3bfdf4c2536_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e269bbc9-4f8c-4043-b484-d3bfdf4c2536" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e269bbc9-4f8c-4043-b484-d3bfdf4c2536_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a07d3a08-ac2b-493f-a9f1-f8e8c01bcc1c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e269bbc9-4f8c-4043-b484-d3bfdf4c2536" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a07d3a08-ac2b-493f-a9f1-f8e8c01bcc1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyEquipmentMember_40b21be1-2286-427b-ba39-12b5f95cc47e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TechnologyEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a07d3a08-ac2b-493f-a9f1-f8e8c01bcc1c" xlink:to="loc_us-gaap_TechnologyEquipmentMember_40b21be1-2286-427b-ba39-12b5f95cc47e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DatabasesMember_e6824675-f260-4499-b3bb-2e08226c7b40" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DatabasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a07d3a08-ac2b-493f-a9f1-f8e8c01bcc1c" xlink:to="loc_us-gaap_DatabasesMember_e6824675-f260-4499-b3bb-2e08226c7b40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_2274d520-4d1c-45ad-93a8-0397fbed37a2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a07d3a08-ac2b-493f-a9f1-f8e8c01bcc1c" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_2274d520-4d1c-45ad-93a8-0397fbed37a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_e5132d76-20c5-491e-904f-d201ff092d69" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a07d3a08-ac2b-493f-a9f1-f8e8c01bcc1c" xlink:to="loc_us-gaap_CustomerRelationshipsMember_e5132d76-20c5-491e-904f-d201ff092d69" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/BusinessCombinationsProFormaRevenueandEarningsofAcquisitionDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#BusinessCombinationsProFormaRevenueandEarningsofAcquisitionDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/BusinessCombinationsProFormaRevenueandEarningsofAcquisitionDetails" xlink:type="extended" id="i9a85f34c38fd4058bdbd265160734ea0_BusinessCombinationsProFormaRevenueandEarningsofAcquisitionDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_831a0764-8cbc-4c82-a6ae-3485ad35afb7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_2361499b-5ee9-4d28-b66a-e465ff4ca24b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_831a0764-8cbc-4c82-a6ae-3485ad35afb7" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_2361499b-5ee9-4d28-b66a-e465ff4ca24b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BusinessAcquisitionProFormaIncomeLossBeforeIncomeTaxes_2dc57858-6c22-4b6d-a3b8-126defd6c024" xlink:href="zi-20201231.xsd#zi_BusinessAcquisitionProFormaIncomeLossBeforeIncomeTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_831a0764-8cbc-4c82-a6ae-3485ad35afb7" xlink:to="loc_zi_BusinessAcquisitionProFormaIncomeLossBeforeIncomeTaxes_2dc57858-6c22-4b6d-a3b8-126defd6c024" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4c435ca1-6943-4e19-87d9-ea7385dc34dc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_831a0764-8cbc-4c82-a6ae-3485ad35afb7" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4c435ca1-6943-4e19-87d9-ea7385dc34dc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_04e1d385-1117-46aa-a9bc-29f643c14b2e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4c435ca1-6943-4e19-87d9-ea7385dc34dc" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_04e1d385-1117-46aa-a9bc-29f643c14b2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_04e1d385-1117-46aa-a9bc-29f643c14b2e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_04e1d385-1117-46aa-a9bc-29f643c14b2e" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_04e1d385-1117-46aa-a9bc-29f643c14b2e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3c0c3680-4217-4bfe-b27f-359327571c4a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_04e1d385-1117-46aa-a9bc-29f643c14b2e" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3c0c3680-4217-4bfe-b27f-359327571c4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreAcquisitionZoomInformationIncMember_64c96394-63c0-4d2c-b178-cdf19631e45c" xlink:href="zi-20201231.xsd#zi_PreAcquisitionZoomInformationIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3c0c3680-4217-4bfe-b27f-359327571c4a" xlink:to="loc_zi_PreAcquisitionZoomInformationIncMember_64c96394-63c0-4d2c-b178-cdf19631e45c" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/CashCashEquivalentsandShorttermInvestments" xlink:type="simple" xlink:href="zi-20201231.xsd#CashCashEquivalentsandShorttermInvestments"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/CashCashEquivalentsandShorttermInvestments" xlink:type="extended" id="id103543cc6954aedaee4a36139de96a8_CashCashEquivalentsandShorttermInvestments"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/CashCashEquivalentsandShorttermInvestmentsTables" xlink:type="simple" xlink:href="zi-20201231.xsd#CashCashEquivalentsandShorttermInvestmentsTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/CashCashEquivalentsandShorttermInvestmentsTables" xlink:type="extended" id="i39693204b6154a5ab407024f396be95d_CashCashEquivalentsandShorttermInvestmentsTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/CashCashEquivalentsandShorttermInvestmentsComponentsDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#CashCashEquivalentsandShorttermInvestmentsComponentsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/CashCashEquivalentsandShorttermInvestmentsComponentsDetails" xlink:type="extended" id="i2dbb87442b65490992dc5d6141a06fda_CashCashEquivalentsandShorttermInvestmentsComponentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesLineItems_ed437d3e-0677-4637-9b1b-8d2c29d56bad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MarketableSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_4df6bee0-90ec-4ce2-aef4-04995c07e821" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_ed437d3e-0677-4637-9b1b-8d2c29d56bad" xlink:to="loc_us-gaap_AssetsCurrentAbstract_4df6bee0-90ec-4ce2-aef4-04995c07e821" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Cash_df27267f-167f-49ea-98b5-8a61c1628a18" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Cash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_4df6bee0-90ec-4ce2-aef4-04995c07e821" xlink:to="loc_us-gaap_Cash_df27267f-167f-49ea-98b5-8a61c1628a18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashEquivalentsAtCarryingValueAbstract_3e836ab1-44f4-47de-b8ff-375d5d357ed2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashEquivalentsAtCarryingValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_4df6bee0-90ec-4ce2-aef4-04995c07e821" xlink:to="loc_us-gaap_CashEquivalentsAtCarryingValueAbstract_3e836ab1-44f4-47de-b8ff-375d5d357ed2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashEquivalentsAtCarryingValue_2467dbd5-b884-49c8-a987-1b0279b57c1e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashEquivalentsAtCarryingValueAbstract_3e836ab1-44f4-47de-b8ff-375d5d357ed2" xlink:to="loc_us-gaap_CashEquivalentsAtCarryingValue_2467dbd5-b884-49c8-a987-1b0279b57c1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_a51509b7-ccbe-44cc-a01e-dbdc990d01a2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_4df6bee0-90ec-4ce2-aef4-04995c07e821" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_a51509b7-ccbe-44cc-a01e-dbdc990d01a2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestmentsAbstract_212e9a6f-a1ff-40dc-b82b-62ba904452bf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortTermInvestmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_ed437d3e-0677-4637-9b1b-8d2c29d56bad" xlink:to="loc_us-gaap_ShortTermInvestmentsAbstract_212e9a6f-a1ff-40dc-b82b-62ba904452bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestments_6c1c04a0-f380-4d05-9701-124033b8df5f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermInvestmentsAbstract_212e9a6f-a1ff-40dc-b82b-62ba904452bf" xlink:to="loc_us-gaap_ShortTermInvestments_6c1c04a0-f380-4d05-9701-124033b8df5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsAndShortTermInvestments_c9859b7b-dc68-4e8a-8311-d934db54cd24" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsAndShortTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_ed437d3e-0677-4637-9b1b-8d2c29d56bad" xlink:to="loc_us-gaap_CashCashEquivalentsAndShortTermInvestments_c9859b7b-dc68-4e8a-8311-d934db54cd24" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesTable_22a20d4f-0d3e-40cc-8a07-997bf5ead461" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MarketableSecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_ed437d3e-0677-4637-9b1b-8d2c29d56bad" xlink:to="loc_us-gaap_MarketableSecuritiesTable_22a20d4f-0d3e-40cc-8a07-997bf5ead461" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_ecb06f35-b10b-4c30-bd5b-5281779ee709" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MarketableSecuritiesTable_22a20d4f-0d3e-40cc-8a07-997bf5ead461" xlink:to="loc_us-gaap_FinancialInstrumentAxis_ecb06f35-b10b-4c30-bd5b-5281779ee709" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ecb06f35-b10b-4c30-bd5b-5281779ee709_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_ecb06f35-b10b-4c30-bd5b-5281779ee709" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ecb06f35-b10b-4c30-bd5b-5281779ee709_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_a79ba502-fe15-44bb-ac0f-984a5d9e438b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_ecb06f35-b10b-4c30-bd5b-5281779ee709" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_a79ba502-fe15-44bb-ac0f-984a5d9e438b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_a07a8acc-b359-475e-b4e5-2457c6fd6550" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_a79ba502-fe15-44bb-ac0f-984a5d9e438b" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_a07a8acc-b359-475e-b4e5-2457c6fd6550" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_8690effd-306c-4150-a043-c73abc1ae24e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_a79ba502-fe15-44bb-ac0f-984a5d9e438b" xlink:to="loc_us-gaap_MoneyMarketFundsMember_8690effd-306c-4150-a043-c73abc1ae24e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_20d8285c-ebb0-4c47-a8d4-b76cd41089ca" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_a79ba502-fe15-44bb-ac0f-984a5d9e438b" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_20d8285c-ebb0-4c47-a8d4-b76cd41089ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_da32d6bc-e655-4554-98b0-80ad98637f91" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_a79ba502-fe15-44bb-ac0f-984a5d9e438b" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_da32d6bc-e655-4554-98b0-80ad98637f91" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/CashCashEquivalentsandShorttermInvestmentsDebtSecuritiesAvailableforsaleUnrealizedLossPositionFairValueDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#CashCashEquivalentsandShorttermInvestmentsDebtSecuritiesAvailableforsaleUnrealizedLossPositionFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/CashCashEquivalentsandShorttermInvestmentsDebtSecuritiesAvailableforsaleUnrealizedLossPositionFairValueDetails" xlink:type="extended" id="i1c02ba9d62624437b61f5ae5c46b28c7_CashCashEquivalentsandShorttermInvestmentsDebtSecuritiesAvailableforsaleUnrealizedLossPositionFairValueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_6a1252c1-de10-4825-97cc-a00a3f839a7e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_1ab941cf-7d4b-4a0d-8357-d90145516491" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_6a1252c1-de10-4825-97cc-a00a3f839a7e" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_1ab941cf-7d4b-4a0d-8357-d90145516491" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_1463e9ee-5fc0-47a5-9c4a-c40dbdae5292" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_6a1252c1-de10-4825-97cc-a00a3f839a7e" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_1463e9ee-5fc0-47a5-9c4a-c40dbdae5292" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions_28caabcd-f37a-4997-90c5-17bdaa5bd3aa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_6a1252c1-de10-4825-97cc-a00a3f839a7e" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions_28caabcd-f37a-4997-90c5-17bdaa5bd3aa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_21d6a831-3d2f-4851-b549-6108773c1858" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_6a1252c1-de10-4825-97cc-a00a3f839a7e" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_21d6a831-3d2f-4851-b549-6108773c1858" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_32da8260-6106-4ce6-905c-47f594df6516" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_21d6a831-3d2f-4851-b549-6108773c1858" xlink:to="loc_us-gaap_FinancialInstrumentAxis_32da8260-6106-4ce6-905c-47f594df6516" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_32da8260-6106-4ce6-905c-47f594df6516_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_32da8260-6106-4ce6-905c-47f594df6516" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_32da8260-6106-4ce6-905c-47f594df6516_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7fb91614-3160-4f09-b31c-e2067e6281a6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_32da8260-6106-4ce6-905c-47f594df6516" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7fb91614-3160-4f09-b31c-e2067e6281a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_ff74a764-135e-42f2-8864-b09034a0fbab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7fb91614-3160-4f09-b31c-e2067e6281a6" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_ff74a764-135e-42f2-8864-b09034a0fbab" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/CashCashEquivalentsandShorttermInvestmentsCostandEstimatedFairValueDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#CashCashEquivalentsandShorttermInvestmentsCostandEstimatedFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/CashCashEquivalentsandShorttermInvestmentsCostandEstimatedFairValueDetails" xlink:type="extended" id="i11ae17b5c64b49e79e7c7a6eb4825ac7_CashCashEquivalentsandShorttermInvestmentsCostandEstimatedFairValueDetails"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/PropertyandEquipment" xlink:type="simple" xlink:href="zi-20201231.xsd#PropertyandEquipment"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/PropertyandEquipment" xlink:type="extended" id="iea3ae34963494ccc8fcd6fa21c2a761a_PropertyandEquipment"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/PropertyandEquipmentTables" xlink:type="simple" xlink:href="zi-20201231.xsd#PropertyandEquipmentTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/PropertyandEquipmentTables" xlink:type="extended" id="i277bf56f7f3d45538d9615793fc21298_PropertyandEquipmentTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/PropertyandEquipmentDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#PropertyandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/PropertyandEquipmentDetails" xlink:type="extended" id="id386cff8bfe943188b3dedc1aed37e27_PropertyandEquipmentDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_57fd8494-e9ff-4443-b936-dc47e3f74387" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_984fd65a-d3d1-4ecd-90ce-b00415794142" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_57fd8494-e9ff-4443-b936-dc47e3f74387" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_984fd65a-d3d1-4ecd-90ce-b00415794142" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_0183275b-d97b-4697-8a10-dee660d49738" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_57fd8494-e9ff-4443-b936-dc47e3f74387" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_0183275b-d97b-4697-8a10-dee660d49738" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_a1a54aa1-4dec-4bfa-97e8-737a89cdc3cb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_57fd8494-e9ff-4443-b936-dc47e3f74387" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_a1a54aa1-4dec-4bfa-97e8-737a89cdc3cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_0e4b8927-5e07-4472-88cb-5b57436c26c9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_57fd8494-e9ff-4443-b936-dc47e3f74387" xlink:to="loc_us-gaap_Depreciation_0e4b8927-5e07-4472-88cb-5b57436c26c9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_b59f7be4-165a-43be-9079-022be6dabffe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_57fd8494-e9ff-4443-b936-dc47e3f74387" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_b59f7be4-165a-43be-9079-022be6dabffe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_08eb0ec9-1b7a-40bb-bac5-5067d8954b01" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_b59f7be4-165a-43be-9079-022be6dabffe" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_08eb0ec9-1b7a-40bb-bac5-5067d8954b01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_08eb0ec9-1b7a-40bb-bac5-5067d8954b01_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_08eb0ec9-1b7a-40bb-bac5-5067d8954b01" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_08eb0ec9-1b7a-40bb-bac5-5067d8954b01_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3495d660-3881-4544-a3fc-d423e6f7fd50" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_08eb0ec9-1b7a-40bb-bac5-5067d8954b01" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3495d660-3881-4544-a3fc-d423e6f7fd50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerEquipmentMember_d9d76df9-ac9c-4cb1-bffe-1216b4026f21" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3495d660-3881-4544-a3fc-d423e6f7fd50" xlink:to="loc_us-gaap_ComputerEquipmentMember_d9d76df9-ac9c-4cb1-bffe-1216b4026f21" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_3c019e68-4c2d-4084-9cac-66758174439d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3495d660-3881-4544-a3fc-d423e6f7fd50" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_3c019e68-4c2d-4084-9cac-66758174439d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_08779ec7-5cff-455f-ac31-e7ef1e6eb4ba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3495d660-3881-4544-a3fc-d423e6f7fd50" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_08779ec7-5cff-455f-ac31-e7ef1e6eb4ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_1c4bb7af-9d05-40b9-ad7e-b067f3d6cf89" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3495d660-3881-4544-a3fc-d423e6f7fd50" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_1c4bb7af-9d05-40b9-ad7e-b067f3d6cf89" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_8353f1f7-712e-4833-b345-ccfe044e2959" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3495d660-3881-4544-a3fc-d423e6f7fd50" xlink:to="loc_us-gaap_ConstructionInProgressMember_8353f1f7-712e-4833-b345-ccfe044e2959" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/GoodwillandAcquiredIntangibleAssets" xlink:type="simple" xlink:href="zi-20201231.xsd#GoodwillandAcquiredIntangibleAssets"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/GoodwillandAcquiredIntangibleAssets" xlink:type="extended" id="i19b651fc79ee4f068af66184f7f381c6_GoodwillandAcquiredIntangibleAssets"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/GoodwillandAcquiredIntangibleAssetsTables" xlink:type="simple" xlink:href="zi-20201231.xsd#GoodwillandAcquiredIntangibleAssetsTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/GoodwillandAcquiredIntangibleAssetsTables" xlink:type="extended" id="i481156d2c9df4be9bd9fa172003f2ce2_GoodwillandAcquiredIntangibleAssetsTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/GoodwillandAcquiredIntangibleAssetsIntangibleAssetsDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#GoodwillandAcquiredIntangibleAssetsIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/GoodwillandAcquiredIntangibleAssetsIntangibleAssetsDetails" xlink:type="extended" id="ie370d9e622ad4e7aace34fea7a6e7f6d_GoodwillandAcquiredIntangibleAssetsIntangibleAssetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_f1af99af-5fc4-4682-a905-e94e05e6236e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_ab16efa4-88a9-4ad7-8601-ad996e9ccf0e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_f1af99af-5fc4-4682-a905-e94e05e6236e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_ab16efa4-88a9-4ad7-8601-ad996e9ccf0e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_68109b53-8f00-4461-ad35-aeb2c2ff6223" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_f1af99af-5fc4-4682-a905-e94e05e6236e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_68109b53-8f00-4461-ad35-aeb2c2ff6223" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_db387fb7-67a9-4a41-94e6-a1462db55a60" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_f1af99af-5fc4-4682-a905-e94e05e6236e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_db387fb7-67a9-4a41-94e6-a1462db55a60" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_7cf15598-b7be-49f9-9fdf-6f09f708541a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_f1af99af-5fc4-4682-a905-e94e05e6236e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_7cf15598-b7be-49f9-9fdf-6f09f708541a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_2dc14724-76e1-443a-9a22-c2038c63c980" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_f1af99af-5fc4-4682-a905-e94e05e6236e" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_2dc14724-76e1-443a-9a22-c2038c63c980" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_17c7d367-db76-46fe-b929-54b49729bb93" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_f1af99af-5fc4-4682-a905-e94e05e6236e" xlink:to="loc_us-gaap_Goodwill_17c7d367-db76-46fe-b929-54b49729bb93" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_2e22fc2e-6b2b-4978-badc-dbe9264f5813" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_f1af99af-5fc4-4682-a905-e94e05e6236e" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_2e22fc2e-6b2b-4978-badc-dbe9264f5813" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_45161f86-6f6a-44f5-81d6-da5e1b972ca4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_f1af99af-5fc4-4682-a905-e94e05e6236e" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_45161f86-6f6a-44f5-81d6-da5e1b972ca4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_ad989a84-7404-476b-8bd8-a490259164c1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_45161f86-6f6a-44f5-81d6-da5e1b972ca4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_ad989a84-7404-476b-8bd8-a490259164c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ad989a84-7404-476b-8bd8-a490259164c1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_ad989a84-7404-476b-8bd8-a490259164c1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ad989a84-7404-476b-8bd8-a490259164c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8a96f750-8031-4849-8223-b6dcf081e17a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_ad989a84-7404-476b-8bd8-a490259164c1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8a96f750-8031-4849-8223-b6dcf081e17a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_30c19f4b-f2e4-4417-883e-ddf3f5e87631" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8a96f750-8031-4849-8223-b6dcf081e17a" xlink:to="loc_us-gaap_CustomerRelationshipsMember_30c19f4b-f2e4-4417-883e-ddf3f5e87631" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_04248dff-7998-4b42-a3df-bb5ee7c67e28" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8a96f750-8031-4849-8223-b6dcf081e17a" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_04248dff-7998-4b42-a3df-bb5ee7c67e28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BrandPortfolioMember_5ba1e409-683e-45f3-a144-161cbcdecec8" xlink:href="zi-20201231.xsd#zi_BrandPortfolioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8a96f750-8031-4849-8223-b6dcf081e17a" xlink:to="loc_zi_BrandPortfolioMember_5ba1e409-683e-45f3-a144-161cbcdecec8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_eabf4b65-9b31-4aa5-b1ad-f38f5a57ee97" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_45161f86-6f6a-44f5-81d6-da5e1b972ca4" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_eabf4b65-9b31-4aa5-b1ad-f38f5a57ee97" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_eabf4b65-9b31-4aa5-b1ad-f38f5a57ee97_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_eabf4b65-9b31-4aa5-b1ad-f38f5a57ee97" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_eabf4b65-9b31-4aa5-b1ad-f38f5a57ee97_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_27ee5bd9-9775-4843-b654-241dcd856aa8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_eabf4b65-9b31-4aa5-b1ad-f38f5a57ee97" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_27ee5bd9-9775-4843-b654-241dcd856aa8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreAcquisitionBrandPortfolioMember_fc36471a-d215-4da2-ab9e-5803baeb2d38" xlink:href="zi-20201231.xsd#zi_PreAcquisitionBrandPortfolioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_27ee5bd9-9775-4843-b654-241dcd856aa8" xlink:to="loc_zi_PreAcquisitionBrandPortfolioMember_fc36471a-d215-4da2-ab9e-5803baeb2d38" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/GoodwillandAcquiredIntangibleAssetsFutureAmortizationExpenseDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#GoodwillandAcquiredIntangibleAssetsFutureAmortizationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/GoodwillandAcquiredIntangibleAssetsFutureAmortizationExpenseDetails" xlink:type="extended" id="i976801f95f8b47778205902ed6ddbf65_GoodwillandAcquiredIntangibleAssetsFutureAmortizationExpenseDetails"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/GoodwillandAcquiredIntangibleAssetsChangestoGoodwillDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#GoodwillandAcquiredIntangibleAssetsChangestoGoodwillDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/GoodwillandAcquiredIntangibleAssetsChangestoGoodwillDetails" xlink:type="extended" id="i5777f29b33e94c17b4c54044bb39ca5d_GoodwillandAcquiredIntangibleAssetsChangestoGoodwillDetails"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/FinancingArrangements" xlink:type="simple" xlink:href="zi-20201231.xsd#FinancingArrangements"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/FinancingArrangements" xlink:type="extended" id="if9551124aea6497aad6989e7df98b0a0_FinancingArrangements"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/FinancingArrangementsTables" xlink:type="simple" xlink:href="zi-20201231.xsd#FinancingArrangementsTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/FinancingArrangementsTables" xlink:type="extended" id="i1af93b7123c74a058a0d9f8d0a796217_FinancingArrangementsTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/FinancingArrangementsCarryingValuesofBorrowingsDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#FinancingArrangementsCarryingValuesofBorrowingsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/FinancingArrangementsCarryingValuesofBorrowingsDetails" xlink:type="extended" id="i99362e44e4ed490094d0fb9e9bcede55_FinancingArrangementsCarryingValuesofBorrowingsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_d501a08a-eb94-4bac-a6d2-d1426b140fd4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_94b25e6f-a5e6-4f33-bf53-0d6d081f23e5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d501a08a-eb94-4bac-a6d2-d1426b140fd4" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_94b25e6f-a5e6-4f33-bf53-0d6d081f23e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_db4428c0-73f0-458c-af1a-ee9495e58e90" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d501a08a-eb94-4bac-a6d2-d1426b140fd4" xlink:to="loc_us-gaap_LongTermDebt_db4428c0-73f0-458c-af1a-ee9495e58e90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_9fe5a4b0-061b-4414-b26c-4688bb70819f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d501a08a-eb94-4bac-a6d2-d1426b140fd4" xlink:to="loc_us-gaap_LineOfCredit_9fe5a4b0-061b-4414-b26c-4688bb70819f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_98fd4e9f-c410-41fe-8872-e711befa4349" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d501a08a-eb94-4bac-a6d2-d1426b140fd4" xlink:to="loc_us-gaap_LongTermDebtCurrent_98fd4e9f-c410-41fe-8872-e711befa4349" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_57481f5d-f8b2-4123-a49c-e13c7b9a03d6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d501a08a-eb94-4bac-a6d2-d1426b140fd4" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_57481f5d-f8b2-4123-a49c-e13c7b9a03d6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_7eca6bf4-5e17-4741-ac69-eafb02e53d19" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d501a08a-eb94-4bac-a6d2-d1426b140fd4" xlink:to="loc_us-gaap_DebtInstrumentTable_7eca6bf4-5e17-4741-ac69-eafb02e53d19" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_cc5d8e66-9862-4b5c-bb7d-5008bfeedbaf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7eca6bf4-5e17-4741-ac69-eafb02e53d19" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_cc5d8e66-9862-4b5c-bb7d-5008bfeedbaf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_cc5d8e66-9862-4b5c-bb7d-5008bfeedbaf_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_cc5d8e66-9862-4b5c-bb7d-5008bfeedbaf" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_cc5d8e66-9862-4b5c-bb7d-5008bfeedbaf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_9474f64c-a6db-483a-b138-3a2b875fcd3f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_cc5d8e66-9862-4b5c-bb7d-5008bfeedbaf" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_9474f64c-a6db-483a-b138-3a2b875fcd3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_f922e6d2-69e9-4ffc-a7b0-ad9ca64ba730" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_9474f64c-a6db-483a-b138-3a2b875fcd3f" xlink:to="loc_us-gaap_SecuredDebtMember_f922e6d2-69e9-4ffc-a7b0-ad9ca64ba730" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_a2ef6160-e3f4-4d4a-b908-0a2378dd52b8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7eca6bf4-5e17-4741-ac69-eafb02e53d19" xlink:to="loc_us-gaap_DebtInstrumentAxis_a2ef6160-e3f4-4d4a-b908-0a2378dd52b8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_a2ef6160-e3f4-4d4a-b908-0a2378dd52b8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_a2ef6160-e3f4-4d4a-b908-0a2378dd52b8" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_a2ef6160-e3f4-4d4a-b908-0a2378dd52b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_554fb91a-05e1-4f88-950b-d1536df0c50f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_a2ef6160-e3f4-4d4a-b908-0a2378dd52b8" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_554fb91a-05e1-4f88-950b-d1536df0c50f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_FirstLienTermLoanMember_26b852ca-6c0e-4c6a-8951-91ecd22d71f0" xlink:href="zi-20201231.xsd#zi_FirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_554fb91a-05e1-4f88-950b-d1536df0c50f" xlink:to="loc_zi_FirstLienTermLoanMember_26b852ca-6c0e-4c6a-8951-91ecd22d71f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_SecondLienTermLoanMember_476a5469-c8f9-4e1f-8a28-529b0ef7ee94" xlink:href="zi-20201231.xsd#zi_SecondLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_554fb91a-05e1-4f88-950b-d1536df0c50f" xlink:to="loc_zi_SecondLienTermLoanMember_476a5469-c8f9-4e1f-8a28-529b0ef7ee94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_ef06b317-e569-490c-95ac-fe99711c2a80" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7eca6bf4-5e17-4741-ac69-eafb02e53d19" xlink:to="loc_us-gaap_CreditFacilityAxis_ef06b317-e569-490c-95ac-fe99711c2a80" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_ef06b317-e569-490c-95ac-fe99711c2a80_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_ef06b317-e569-490c-95ac-fe99711c2a80" xlink:to="loc_us-gaap_CreditFacilityDomain_ef06b317-e569-490c-95ac-fe99711c2a80_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_5e9d3d36-78aa-4923-a388-f5a563a75857" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_ef06b317-e569-490c-95ac-fe99711c2a80" xlink:to="loc_us-gaap_CreditFacilityDomain_5e9d3d36-78aa-4923-a388-f5a563a75857" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_99b1f9f3-d273-4ca8-a910-0b9359726b8d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_5e9d3d36-78aa-4923-a388-f5a563a75857" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_99b1f9f3-d273-4ca8-a910-0b9359726b8d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/FinancingArrangementsNarrativeDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#FinancingArrangementsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/FinancingArrangementsNarrativeDetails" xlink:type="extended" id="i11fa60aeac764699973e91eae909a514_FinancingArrangementsNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_bb27fb7d-6742-4ec8-8e87-4f49f6f8bbb0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_bb27fb7d-6742-4ec8-8e87-4f49f6f8bbb0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateIncreaseDecrease_55bf50f8-f459-40c9-b46d-0b03f1acb0e8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_DebtInstrumentInterestRateIncreaseDecrease_55bf50f8-f459-40c9-b46d-0b03f1acb0e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_ed2a93da-8ce1-4e65-ac35-cd6df2c8607f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_ed2a93da-8ce1-4e65-ac35-cd6df2c8607f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_b58bdbd5-5ded-4207-988c-71b65e7859d2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_b58bdbd5-5ded-4207-988c-71b65e7859d2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_e7e85ce2-669d-49f7-b1c4-87876b487133" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentRepurchasedFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_e7e85ce2-669d-49f7-b1c4-87876b487133" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrentAndNoncurrent_ae632b8e-1e1d-4c20-921a-bcf5dba0c298" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestPayableCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_InterestPayableCurrentAndNoncurrent_ae632b8e-1e1d-4c20-921a-bcf5dba0c298" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_dff55d7b-94ec-43e8-9056-cdeb17b0208f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_dff55d7b-94ec-43e8-9056-cdeb17b0208f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_1463bb6f-3f02-4605-9d75-4ba299b50fcc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_1463bb6f-3f02-4605-9d75-4ba299b50fcc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_40bf58e7-cb3a-4777-9b67-08dc9c4745dd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_40bf58e7-cb3a-4777-9b67-08dc9c4745dd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_ccd30952-2d91-4b98-9577-9c6f4c8c6e1d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_ccd30952-2d91-4b98-9577-9c6f4c8c6e1d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_GainLossOnExtinguishmentOfDebtIncludingWriteOffOfUnamortizedIssuanceCostsAndPrepaymentPenalty_a36ff1db-8f77-438f-a2a5-578554c8c43a" xlink:href="zi-20201231.xsd#zi_GainLossOnExtinguishmentOfDebtIncludingWriteOffOfUnamortizedIssuanceCostsAndPrepaymentPenalty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_zi_GainLossOnExtinguishmentOfDebtIncludingWriteOffOfUnamortizedIssuanceCostsAndPrepaymentPenalty_a36ff1db-8f77-438f-a2a5-578554c8c43a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_67d3d7cb-a916-484b-a8a0-5ba00380cb64" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_67d3d7cb-a916-484b-a8a0-5ba00380cb64" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExtinguishmentOfDebtAmount_5163be26-a32d-465a-acc0-cacc2b5e020d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ExtinguishmentOfDebtAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_ExtinguishmentOfDebtAmount_5163be26-a32d-465a-acc0-cacc2b5e020d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_DebtInstrumentCovenantThresholdDrawsOnLineOfCreditToTriggerSpringingFinancialCovenant_13044387-7ed4-4d13-948f-1509529f8f14" xlink:href="zi-20201231.xsd#zi_DebtInstrumentCovenantThresholdDrawsOnLineOfCreditToTriggerSpringingFinancialCovenant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_zi_DebtInstrumentCovenantThresholdDrawsOnLineOfCreditToTriggerSpringingFinancialCovenant_13044387-7ed4-4d13-948f-1509529f8f14" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_DebtInstrumentCovenantLeverageRatioMaximum_6644434a-815e-4140-aabd-55b4ea4f7b45" xlink:href="zi-20201231.xsd#zi_DebtInstrumentCovenantLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_zi_DebtInstrumentCovenantLeverageRatioMaximum_6644434a-815e-4140-aabd-55b4ea4f7b45" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_b8660622-7b7f-4b43-a970-540462f026c1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_b8660622-7b7f-4b43-a970-540462f026c1" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_a4f022d7-6187-4936-a36a-18aac897c055" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_a4f022d7-6187-4936-a36a-18aac897c055" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_9e67f7b8-c5f8-4a18-afc0-fa99a3d1e262" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0199d0e8-fae4-4df9-a87b-0652274f8860" xlink:to="loc_us-gaap_DebtInstrumentTable_9e67f7b8-c5f8-4a18-afc0-fa99a3d1e262" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_a872cb9d-3fed-462d-94bf-0efb6863c3fd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_9e67f7b8-c5f8-4a18-afc0-fa99a3d1e262" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_a872cb9d-3fed-462d-94bf-0efb6863c3fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_a872cb9d-3fed-462d-94bf-0efb6863c3fd_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_a872cb9d-3fed-462d-94bf-0efb6863c3fd" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_a872cb9d-3fed-462d-94bf-0efb6863c3fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_80bb7e7b-0637-49e1-9645-5c81e839d6ec" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_a872cb9d-3fed-462d-94bf-0efb6863c3fd" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_80bb7e7b-0637-49e1-9645-5c81e839d6ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_db829ace-2156-4a4c-9d84-9adf18ec65c1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_80bb7e7b-0637-49e1-9645-5c81e839d6ec" xlink:to="loc_us-gaap_SecuredDebtMember_db829ace-2156-4a4c-9d84-9adf18ec65c1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_0cd7ecec-8305-4522-8493-c5e95d86b075" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_9e67f7b8-c5f8-4a18-afc0-fa99a3d1e262" xlink:to="loc_us-gaap_DebtInstrumentAxis_0cd7ecec-8305-4522-8493-c5e95d86b075" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_0cd7ecec-8305-4522-8493-c5e95d86b075_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_0cd7ecec-8305-4522-8493-c5e95d86b075" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_0cd7ecec-8305-4522-8493-c5e95d86b075_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_c45d4acd-de67-4afe-ac6c-29394730120e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_0cd7ecec-8305-4522-8493-c5e95d86b075" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_c45d4acd-de67-4afe-ac6c-29394730120e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_FirstLienTermLoanMember_84e153b5-805e-4c49-b8c2-fc79ec5cc3ca" xlink:href="zi-20201231.xsd#zi_FirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_c45d4acd-de67-4afe-ac6c-29394730120e" xlink:to="loc_zi_FirstLienTermLoanMember_84e153b5-805e-4c49-b8c2-fc79ec5cc3ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_SecondLienTermLoanMember_107bd5f9-00ce-4307-a9db-3541baa1cda5" xlink:href="zi-20201231.xsd#zi_SecondLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_c45d4acd-de67-4afe-ac6c-29394730120e" xlink:to="loc_zi_SecondLienTermLoanMember_107bd5f9-00ce-4307-a9db-3541baa1cda5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_2cdf0169-0c98-4598-9f6e-e08dc77af98c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_9e67f7b8-c5f8-4a18-afc0-fa99a3d1e262" xlink:to="loc_us-gaap_VariableRateAxis_2cdf0169-0c98-4598-9f6e-e08dc77af98c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_2cdf0169-0c98-4598-9f6e-e08dc77af98c_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_2cdf0169-0c98-4598-9f6e-e08dc77af98c" xlink:to="loc_us-gaap_VariableRateDomain_2cdf0169-0c98-4598-9f6e-e08dc77af98c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_08ffb4eb-5c99-45ea-b583-20c6cd2fa4c1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_2cdf0169-0c98-4598-9f6e-e08dc77af98c" xlink:to="loc_us-gaap_VariableRateDomain_08ffb4eb-5c99-45ea-b583-20c6cd2fa4c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_646890ab-0492-4809-a5fb-99315180eec4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_08ffb4eb-5c99-45ea-b583-20c6cd2fa4c1" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_646890ab-0492-4809-a5fb-99315180eec4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_d8c9c3ae-b549-471e-a914-bcaacf1ccb80" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_08ffb4eb-5c99-45ea-b583-20c6cd2fa4c1" xlink:to="loc_us-gaap_BaseRateMember_d8c9c3ae-b549-471e-a914-bcaacf1ccb80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_b9c08cdd-76dd-41fc-b6ac-1e4bedd90288" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_9e67f7b8-c5f8-4a18-afc0-fa99a3d1e262" xlink:to="loc_srt_RangeAxis_b9c08cdd-76dd-41fc-b6ac-1e4bedd90288" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b9c08cdd-76dd-41fc-b6ac-1e4bedd90288_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_b9c08cdd-76dd-41fc-b6ac-1e4bedd90288" xlink:to="loc_srt_RangeMember_b9c08cdd-76dd-41fc-b6ac-1e4bedd90288_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c37c13ae-7969-4ee7-97fd-941e2a141af0" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_b9c08cdd-76dd-41fc-b6ac-1e4bedd90288" xlink:to="loc_srt_RangeMember_c37c13ae-7969-4ee7-97fd-941e2a141af0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_178d6929-14b8-440e-be3f-409fb068ce77" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c37c13ae-7969-4ee7-97fd-941e2a141af0" xlink:to="loc_srt_MinimumMember_178d6929-14b8-440e-be3f-409fb068ce77" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_bc2d8553-7a8d-4fcd-b4c2-7f143bac2ed4" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c37c13ae-7969-4ee7-97fd-941e2a141af0" xlink:to="loc_srt_MaximumMember_bc2d8553-7a8d-4fcd-b4c2-7f143bac2ed4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_21f2d90f-ecf1-4071-8264-e8053b3da91e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_9e67f7b8-c5f8-4a18-afc0-fa99a3d1e262" xlink:to="loc_us-gaap_CreditFacilityAxis_21f2d90f-ecf1-4071-8264-e8053b3da91e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_21f2d90f-ecf1-4071-8264-e8053b3da91e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_21f2d90f-ecf1-4071-8264-e8053b3da91e" xlink:to="loc_us-gaap_CreditFacilityDomain_21f2d90f-ecf1-4071-8264-e8053b3da91e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_7a099e8e-d875-42e4-8d80-69b117e7bf47" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_21f2d90f-ecf1-4071-8264-e8053b3da91e" xlink:to="loc_us-gaap_CreditFacilityDomain_7a099e8e-d875-42e4-8d80-69b117e7bf47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_de453ec0-fa84-45b1-87e6-12e9bd6c05ec" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_7a099e8e-d875-42e4-8d80-69b117e7bf47" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_de453ec0-fa84-45b1-87e6-12e9bd6c05ec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_89f0c66f-f5fe-4d18-9814-4188acaeb486" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_9e67f7b8-c5f8-4a18-afc0-fa99a3d1e262" xlink:to="loc_us-gaap_StatementClassOfStockAxis_89f0c66f-f5fe-4d18-9814-4188acaeb486" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_89f0c66f-f5fe-4d18-9814-4188acaeb486_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_89f0c66f-f5fe-4d18-9814-4188acaeb486" xlink:to="loc_us-gaap_ClassOfStockDomain_89f0c66f-f5fe-4d18-9814-4188acaeb486_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a5a53316-8a43-4b48-97c2-7eabdf56d465" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_89f0c66f-f5fe-4d18-9814-4188acaeb486" xlink:to="loc_us-gaap_ClassOfStockDomain_a5a53316-8a43-4b48-97c2-7eabdf56d465" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_RedeemableSeriesAPreferredUnitsMember_9ef4e052-b62a-460a-941e-1a0259306d1f" xlink:href="zi-20201231.xsd#zi_RedeemableSeriesAPreferredUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a5a53316-8a43-4b48-97c2-7eabdf56d465" xlink:to="loc_zi_RedeemableSeriesAPreferredUnitsMember_9ef4e052-b62a-460a-941e-1a0259306d1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_9404fcac-e1a6-4143-bfb5-327c19c55ba5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_9e67f7b8-c5f8-4a18-afc0-fa99a3d1e262" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_9404fcac-e1a6-4143-bfb5-327c19c55ba5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_9404fcac-e1a6-4143-bfb5-327c19c55ba5_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_9404fcac-e1a6-4143-bfb5-327c19c55ba5" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_9404fcac-e1a6-4143-bfb5-327c19c55ba5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_f5c8ae33-87ee-4b37-a1a5-79b53765d1cb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_9404fcac-e1a6-4143-bfb5-327c19c55ba5" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_f5c8ae33-87ee-4b37-a1a5-79b53765d1cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_SaleOfStockInConnectionWithAcquisitionMember_ec4b4cb1-a921-48f2-9de7-c86997df45ce" xlink:href="zi-20201231.xsd#zi_SaleOfStockInConnectionWithAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_f5c8ae33-87ee-4b37-a1a5-79b53765d1cb" xlink:to="loc_zi_SaleOfStockInConnectionWithAcquisitionMember_ec4b4cb1-a921-48f2-9de7-c86997df45ce" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/FinancingArrangementsExpectedFuturePrincipalPaymentsforBorrowingsDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#FinancingArrangementsExpectedFuturePrincipalPaymentsforBorrowingsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/FinancingArrangementsExpectedFuturePrincipalPaymentsforBorrowingsDetails" xlink:type="extended" id="i28574683984c41f28b8bf33e940ff6bd_FinancingArrangementsExpectedFuturePrincipalPaymentsforBorrowingsDetails"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/DerivativesandHedgingActivities" xlink:type="simple" xlink:href="zi-20201231.xsd#DerivativesandHedgingActivities"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/DerivativesandHedgingActivities" xlink:type="extended" id="i3b43b353a49e46ba9d472c62dafc3360_DerivativesandHedgingActivities"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesTables" xlink:type="simple" xlink:href="zi-20201231.xsd#DerivativesandHedgingActivitiesTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesTables" xlink:type="extended" id="i4284d497d2f64e879e4f2872088c9a48_DerivativesandHedgingActivitiesTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesNarrativeDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#DerivativesandHedgingActivitiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesNarrativeDetails" xlink:type="extended" id="i01e04a1dcd884c42ae74f57532f8f1c9_DerivativesandHedgingActivitiesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_20583076-7e18-45ff-aa0d-6b2b88768965" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_b2a6bd88-04b2-47d9-81a6-192809531ab2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeNumberOfInstrumentsHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_20583076-7e18-45ff-aa0d-6b2b88768965" xlink:to="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_b2a6bd88-04b2-47d9-81a6-192809531ab2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_23cc00af-8bad-4136-84be-a149a4b17e13" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_20583076-7e18-45ff-aa0d-6b2b88768965" xlink:to="loc_us-gaap_DerivativeNotionalAmount_23cc00af-8bad-4136-84be-a149a4b17e13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_4bf66511-0297-4003-96d3-abf647604060" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_20583076-7e18-45ff-aa0d-6b2b88768965" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_4bf66511-0297-4003-96d3-abf647604060" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_210aa737-e8a7-402a-ba70-7fb4d96b3158" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentRepurchasedFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_20583076-7e18-45ff-aa0d-6b2b88768965" xlink:to="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_210aa737-e8a7-402a-ba70-7fb4d96b3158" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_DebtInstrumentAmountNotRedesignatedForWhichForecastedInterestPaymentsAreNotProbableToOccur_171ca894-ccbf-4cad-bf73-cfed5477fe7c" xlink:href="zi-20201231.xsd#zi_DebtInstrumentAmountNotRedesignatedForWhichForecastedInterestPaymentsAreNotProbableToOccur"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_20583076-7e18-45ff-aa0d-6b2b88768965" xlink:to="loc_zi_DebtInstrumentAmountNotRedesignatedForWhichForecastedInterestPaymentsAreNotProbableToOccur_171ca894-ccbf-4cad-bf73-cfed5477fe7c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet_fdba1144-13ea-4808-bfa7-2257018d9e99" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_20583076-7e18-45ff-aa0d-6b2b88768965" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet_fdba1144-13ea-4808-bfa7-2257018d9e99" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_29dcd7e3-ec35-48fd-9389-824d95e2f125" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_20583076-7e18-45ff-aa0d-6b2b88768965" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_29dcd7e3-ec35-48fd-9389-824d95e2f125" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_b3523cf6-e160-4102-afd2-a3a0d43fbca2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_20583076-7e18-45ff-aa0d-6b2b88768965" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_b3523cf6-e160-4102-afd2-a3a0d43fbca2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_acabdd24-a5e7-4867-952e-15cd19c155f2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_b3523cf6-e160-4102-afd2-a3a0d43fbca2" xlink:to="loc_us-gaap_HedgingDesignationAxis_acabdd24-a5e7-4867-952e-15cd19c155f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_acabdd24-a5e7-4867-952e-15cd19c155f2_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_acabdd24-a5e7-4867-952e-15cd19c155f2" xlink:to="loc_us-gaap_HedgingDesignationDomain_acabdd24-a5e7-4867-952e-15cd19c155f2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_05150ea6-bb4b-40d8-bbcf-c5f84f71973f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_acabdd24-a5e7-4867-952e-15cd19c155f2" xlink:to="loc_us-gaap_HedgingDesignationDomain_05150ea6-bb4b-40d8-bbcf-c5f84f71973f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_441efc3e-1106-4c1d-a517-78f5ae72b272" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_05150ea6-bb4b-40d8-bbcf-c5f84f71973f" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_441efc3e-1106-4c1d-a517-78f5ae72b272" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_5fbbbfb4-5b58-4c11-b938-51ad2b30e1ed" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_05150ea6-bb4b-40d8-bbcf-c5f84f71973f" xlink:to="loc_us-gaap_NondesignatedMember_5fbbbfb4-5b58-4c11-b938-51ad2b30e1ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_c1cf8156-58f6-4acd-ac1c-16cddedd4730" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_b3523cf6-e160-4102-afd2-a3a0d43fbca2" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_c1cf8156-58f6-4acd-ac1c-16cddedd4730" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_c1cf8156-58f6-4acd-ac1c-16cddedd4730_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_c1cf8156-58f6-4acd-ac1c-16cddedd4730" xlink:to="loc_us-gaap_HedgingRelationshipDomain_c1cf8156-58f6-4acd-ac1c-16cddedd4730_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_b5da13e6-099a-4263-9466-c2fded19ab0d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_c1cf8156-58f6-4acd-ac1c-16cddedd4730" xlink:to="loc_us-gaap_HedgingRelationshipDomain_b5da13e6-099a-4263-9466-c2fded19ab0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_47646515-60e5-4b2d-a96d-eb10c97425a6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_b5da13e6-099a-4263-9466-c2fded19ab0d" xlink:to="loc_us-gaap_CashFlowHedgingMember_47646515-60e5-4b2d-a96d-eb10c97425a6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_1a1cfe0b-49f7-467a-9678-cc89c15fd04e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_b3523cf6-e160-4102-afd2-a3a0d43fbca2" xlink:to="loc_us-gaap_DebtInstrumentAxis_1a1cfe0b-49f7-467a-9678-cc89c15fd04e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_1a1cfe0b-49f7-467a-9678-cc89c15fd04e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_1a1cfe0b-49f7-467a-9678-cc89c15fd04e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_1a1cfe0b-49f7-467a-9678-cc89c15fd04e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_38117548-4f52-4a84-aa74-213a1329a354" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_1a1cfe0b-49f7-467a-9678-cc89c15fd04e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_38117548-4f52-4a84-aa74-213a1329a354" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_FirstLienTermLoanMember_5900e32b-6b3b-43d0-8dd6-3fd18fdb6612" xlink:href="zi-20201231.xsd#zi_FirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_38117548-4f52-4a84-aa74-213a1329a354" xlink:to="loc_zi_FirstLienTermLoanMember_5900e32b-6b3b-43d0-8dd6-3fd18fdb6612" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_29c0b8ed-96d7-4385-80ef-a57821b5aa08" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_b3523cf6-e160-4102-afd2-a3a0d43fbca2" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_29c0b8ed-96d7-4385-80ef-a57821b5aa08" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_29c0b8ed-96d7-4385-80ef-a57821b5aa08_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_29c0b8ed-96d7-4385-80ef-a57821b5aa08" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_29c0b8ed-96d7-4385-80ef-a57821b5aa08_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_23a1e19e-7ecb-403e-969e-e168acf00575" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_29c0b8ed-96d7-4385-80ef-a57821b5aa08" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_23a1e19e-7ecb-403e-969e-e168acf00575" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_1ec91644-6d76-4603-9473-620b357a44f2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_23a1e19e-7ecb-403e-969e-e168acf00575" xlink:to="loc_us-gaap_SecuredDebtMember_1ec91644-6d76-4603-9473-620b357a44f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_c0d098bd-7042-4ed8-a4d1-9fbf6867f8e0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_b3523cf6-e160-4102-afd2-a3a0d43fbca2" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_c0d098bd-7042-4ed8-a4d1-9fbf6867f8e0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_c0d098bd-7042-4ed8-a4d1-9fbf6867f8e0_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_c0d098bd-7042-4ed8-a4d1-9fbf6867f8e0" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_c0d098bd-7042-4ed8-a4d1-9fbf6867f8e0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_a69d3656-c457-4203-886c-b03d3a040cc0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_c0d098bd-7042-4ed8-a4d1-9fbf6867f8e0" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_a69d3656-c457-4203-886c-b03d3a040cc0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_962a57af-d3c4-4b52-a6a8-8bf5ce6e335d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_a69d3656-c457-4203-886c-b03d3a040cc0" xlink:to="loc_us-gaap_InterestRateSwapMember_962a57af-d3c4-4b52-a6a8-8bf5ce6e335d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCapMember_cf6fea50-90ec-4d46-8016-b666eb65320d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateCapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_a69d3656-c457-4203-886c-b03d3a040cc0" xlink:to="loc_us-gaap_InterestRateCapMember_cf6fea50-90ec-4d46-8016-b666eb65320d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForwardContractsMember_d5ad43a8-7e4d-4190-bfd0-89a8c52a3c7d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ForwardContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_a69d3656-c457-4203-886c-b03d3a040cc0" xlink:to="loc_us-gaap_ForwardContractsMember_d5ad43a8-7e4d-4190-bfd0-89a8c52a3c7d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_FirstLienTermLoanMember_579d71e6-5cba-4561-bcd5-53e90a49fabf" xlink:href="zi-20201231.xsd#zi_FirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_a69d3656-c457-4203-886c-b03d3a040cc0" xlink:to="loc_zi_FirstLienTermLoanMember_579d71e6-5cba-4561-bcd5-53e90a49fabf" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesOutstandingInterestRateDerivativesDesignatedasCashFlowHedgesofInterestRateRiskDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#DerivativesandHedgingActivitiesOutstandingInterestRateDerivativesDesignatedasCashFlowHedgesofInterestRateRiskDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesOutstandingInterestRateDerivativesDesignatedasCashFlowHedgesofInterestRateRiskDetails" xlink:type="extended" id="ia80d53d26fbf457c886a230820c04cce_DerivativesandHedgingActivitiesOutstandingInterestRateDerivativesDesignatedasCashFlowHedgesofInterestRateRiskDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_afd064b4-3d87-4650-a88e-1f06762d6e7f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_9aa8b0f1-6861-4b01-bc72-02d3dbff09f5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeNumberOfInstrumentsHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_afd064b4-3d87-4650-a88e-1f06762d6e7f" xlink:to="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_9aa8b0f1-6861-4b01-bc72-02d3dbff09f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_80dfc328-b693-4e45-9c30-077b6742621c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_afd064b4-3d87-4650-a88e-1f06762d6e7f" xlink:to="loc_us-gaap_DerivativeNotionalAmount_80dfc328-b693-4e45-9c30-077b6742621c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCapInterestRate_f791ca80-7f95-4884-a079-4f03a30d0936" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeCapInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_afd064b4-3d87-4650-a88e-1f06762d6e7f" xlink:to="loc_us-gaap_DerivativeCapInterestRate_f791ca80-7f95-4884-a079-4f03a30d0936" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAverageFixedInterestRate_02475e18-7b6d-42db-9a00-618382cac261" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeAverageFixedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_afd064b4-3d87-4650-a88e-1f06762d6e7f" xlink:to="loc_us-gaap_DerivativeAverageFixedInterestRate_02475e18-7b6d-42db-9a00-618382cac261" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_c83184e0-8ad3-4703-9476-1158404ce095" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_afd064b4-3d87-4650-a88e-1f06762d6e7f" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_c83184e0-8ad3-4703-9476-1158404ce095" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_5170bebd-12f0-496a-995c-0350c7270fcf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_c83184e0-8ad3-4703-9476-1158404ce095" xlink:to="loc_us-gaap_HedgingDesignationAxis_5170bebd-12f0-496a-995c-0350c7270fcf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_5170bebd-12f0-496a-995c-0350c7270fcf_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_5170bebd-12f0-496a-995c-0350c7270fcf" xlink:to="loc_us-gaap_HedgingDesignationDomain_5170bebd-12f0-496a-995c-0350c7270fcf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_1670362d-b8d6-4b3a-9cf9-930ef65da82f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_5170bebd-12f0-496a-995c-0350c7270fcf" xlink:to="loc_us-gaap_HedgingDesignationDomain_1670362d-b8d6-4b3a-9cf9-930ef65da82f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_8d9d2f21-da0a-45ee-9a30-150223eb06e8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_1670362d-b8d6-4b3a-9cf9-930ef65da82f" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_8d9d2f21-da0a-45ee-9a30-150223eb06e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_d60a2cec-c254-47cf-b42a-c1d7b5daa608" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_c83184e0-8ad3-4703-9476-1158404ce095" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_d60a2cec-c254-47cf-b42a-c1d7b5daa608" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_d60a2cec-c254-47cf-b42a-c1d7b5daa608_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_d60a2cec-c254-47cf-b42a-c1d7b5daa608" xlink:to="loc_us-gaap_HedgingRelationshipDomain_d60a2cec-c254-47cf-b42a-c1d7b5daa608_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_7534450d-6f91-4947-bab5-54cd9f7f5fa2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_d60a2cec-c254-47cf-b42a-c1d7b5daa608" xlink:to="loc_us-gaap_HedgingRelationshipDomain_7534450d-6f91-4947-bab5-54cd9f7f5fa2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_4715dd53-c97a-4f95-b517-a658ef44a0c0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_7534450d-6f91-4947-bab5-54cd9f7f5fa2" xlink:to="loc_us-gaap_CashFlowHedgingMember_4715dd53-c97a-4f95-b517-a658ef44a0c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_665114d6-c3f3-4238-b316-66f347da3468" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_c83184e0-8ad3-4703-9476-1158404ce095" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_665114d6-c3f3-4238-b316-66f347da3468" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_665114d6-c3f3-4238-b316-66f347da3468_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_665114d6-c3f3-4238-b316-66f347da3468" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_665114d6-c3f3-4238-b316-66f347da3468_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_cf786e3a-c5c0-44d8-a67c-c3652b3d92f7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_665114d6-c3f3-4238-b316-66f347da3468" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_cf786e3a-c5c0-44d8-a67c-c3652b3d92f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCapMember_5fac71ce-d0c4-4e98-a2ad-cfcb4de8b94a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateCapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_cf786e3a-c5c0-44d8-a67c-c3652b3d92f7" xlink:to="loc_us-gaap_InterestRateCapMember_5fac71ce-d0c4-4e98-a2ad-cfcb4de8b94a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_ae0dbba6-5f41-420e-9028-dbb47b8198f3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_cf786e3a-c5c0-44d8-a67c-c3652b3d92f7" xlink:to="loc_us-gaap_InterestRateSwapMember_ae0dbba6-5f41-420e-9028-dbb47b8198f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForwardContractsMember_472eaf80-1215-4383-9b68-2a56bab527a9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ForwardContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_cf786e3a-c5c0-44d8-a67c-c3652b3d92f7" xlink:to="loc_us-gaap_ForwardContractsMember_472eaf80-1215-4383-9b68-2a56bab527a9" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesFairValueandPresentationintheConsolidatedBalanceSheetsforDerivativesDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#DerivativesandHedgingActivitiesFairValueandPresentationintheConsolidatedBalanceSheetsforDerivativesDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesFairValueandPresentationintheConsolidatedBalanceSheetsforDerivativesDetails" xlink:type="extended" id="i34f3b02d645543a8adcb43eb4a788430_DerivativesandHedgingActivitiesFairValueandPresentationintheConsolidatedBalanceSheetsforDerivativesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_70e4afc7-1db4-4ae5-bcf6-130bf9ae9d19" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_3983dc53-460c-4317-9d82-0acdea8c7025" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_70e4afc7-1db4-4ae5-bcf6-130bf9ae9d19" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_3983dc53-460c-4317-9d82-0acdea8c7025" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_d6099351-ffbc-43d9-bca1-6cf80bbd52f6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_70e4afc7-1db4-4ae5-bcf6-130bf9ae9d19" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_d6099351-ffbc-43d9-bca1-6cf80bbd52f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_06206aee-a32e-4831-a6f4-f673c2305183" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_70e4afc7-1db4-4ae5-bcf6-130bf9ae9d19" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_06206aee-a32e-4831-a6f4-f673c2305183" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_d7d634d2-beb1-4e20-8072-7dc8ed1d4aa6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_06206aee-a32e-4831-a6f4-f673c2305183" xlink:to="loc_us-gaap_HedgingDesignationAxis_d7d634d2-beb1-4e20-8072-7dc8ed1d4aa6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_d7d634d2-beb1-4e20-8072-7dc8ed1d4aa6_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_d7d634d2-beb1-4e20-8072-7dc8ed1d4aa6" xlink:to="loc_us-gaap_HedgingDesignationDomain_d7d634d2-beb1-4e20-8072-7dc8ed1d4aa6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_ac08c5c2-14f7-487b-a905-95b5fc13cdfc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_d7d634d2-beb1-4e20-8072-7dc8ed1d4aa6" xlink:to="loc_us-gaap_HedgingDesignationDomain_ac08c5c2-14f7-487b-a905-95b5fc13cdfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_ee7fe91c-789f-4cd0-8efe-807e2e27bd69" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_ac08c5c2-14f7-487b-a905-95b5fc13cdfc" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_ee7fe91c-789f-4cd0-8efe-807e2e27bd69" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_54029d6a-91cc-4f4f-a241-5f94f2f9b76b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_ac08c5c2-14f7-487b-a905-95b5fc13cdfc" xlink:to="loc_us-gaap_NondesignatedMember_54029d6a-91cc-4f4f-a241-5f94f2f9b76b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_c6e5fa1b-256b-45e9-820c-f5b2214d151e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_06206aee-a32e-4831-a6f4-f673c2305183" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_c6e5fa1b-256b-45e9-820c-f5b2214d151e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_c6e5fa1b-256b-45e9-820c-f5b2214d151e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_c6e5fa1b-256b-45e9-820c-f5b2214d151e" xlink:to="loc_us-gaap_HedgingRelationshipDomain_c6e5fa1b-256b-45e9-820c-f5b2214d151e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_46597919-eb56-4d5c-925c-49365ab68908" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_c6e5fa1b-256b-45e9-820c-f5b2214d151e" xlink:to="loc_us-gaap_HedgingRelationshipDomain_46597919-eb56-4d5c-925c-49365ab68908" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_ce100019-7d90-425d-a5b2-9692b8e394ef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_46597919-eb56-4d5c-925c-49365ab68908" xlink:to="loc_us-gaap_CashFlowHedgingMember_ce100019-7d90-425d-a5b2-9692b8e394ef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_60b3d02b-2e76-4284-b551-00aa21b6292e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_06206aee-a32e-4831-a6f4-f673c2305183" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_60b3d02b-2e76-4284-b551-00aa21b6292e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_60b3d02b-2e76-4284-b551-00aa21b6292e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_60b3d02b-2e76-4284-b551-00aa21b6292e" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_60b3d02b-2e76-4284-b551-00aa21b6292e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_fac50693-e15f-46fb-84ca-c553d1f839d9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_60b3d02b-2e76-4284-b551-00aa21b6292e" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_fac50693-e15f-46fb-84ca-c553d1f839d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_AccruedLiabilitiesCurrentMember_f6c6f6bf-f61a-4931-9249-de532433eda8" xlink:href="zi-20201231.xsd#zi_AccruedLiabilitiesCurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_fac50693-e15f-46fb-84ca-c553d1f839d9" xlink:to="loc_zi_AccruedLiabilitiesCurrentMember_f6c6f6bf-f61a-4931-9249-de532433eda8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_f6ed0b30-7171-4560-bd5e-986f27f21077" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_fac50693-e15f-46fb-84ca-c553d1f839d9" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_f6ed0b30-7171-4560-bd5e-986f27f21077" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_8ad0c86e-6167-434a-a71f-c846a86f90d6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_06206aee-a32e-4831-a6f4-f673c2305183" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_8ad0c86e-6167-434a-a71f-c846a86f90d6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_8ad0c86e-6167-434a-a71f-c846a86f90d6_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_8ad0c86e-6167-434a-a71f-c846a86f90d6" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_8ad0c86e-6167-434a-a71f-c846a86f90d6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_af71e46c-9e26-4257-aebe-5dd8bca00e46" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_8ad0c86e-6167-434a-a71f-c846a86f90d6" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_af71e46c-9e26-4257-aebe-5dd8bca00e46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCapMember_9dc7989f-fed6-4308-ad1f-4463df5424e8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateCapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_af71e46c-9e26-4257-aebe-5dd8bca00e46" xlink:to="loc_us-gaap_InterestRateCapMember_9dc7989f-fed6-4308-ad1f-4463df5424e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_b07d9991-cdc3-4848-bffc-229a6ac53e0a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_af71e46c-9e26-4257-aebe-5dd8bca00e46" xlink:to="loc_us-gaap_InterestRateSwapMember_b07d9991-cdc3-4848-bffc-229a6ac53e0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForwardContractsMember_c4027a7a-ac73-4964-ba82-0a7e4db120bb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ForwardContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_af71e46c-9e26-4257-aebe-5dd8bca00e46" xlink:to="loc_us-gaap_ForwardContractsMember_c4027a7a-ac73-4964-ba82-0a7e4db120bb" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/FairValue" xlink:type="simple" xlink:href="zi-20201231.xsd#FairValue"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/FairValue" xlink:type="extended" id="i3d5d5f4afb244f7ca28d0414361606c9_FairValue"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/FairValueTables" xlink:type="simple" xlink:href="zi-20201231.xsd#FairValueTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/FairValueTables" xlink:type="extended" id="i408aa2b95a5f4cdcbde67fa19f81c63b_FairValueTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/FairValueDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#FairValueDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/FairValueDetails" xlink:type="extended" id="i942c34392f404008b1998c6be139fb4a_FairValueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0975546c-5282-4482-b2e5-803cc664e66c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashEquivalentsAtCarryingValue_50977e37-6aed-4ed0-bf37-862e800a5e8b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0975546c-5282-4482-b2e5-803cc664e66c" xlink:to="loc_us-gaap_CashEquivalentsAtCarryingValue_50977e37-6aed-4ed0-bf37-862e800a5e8b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestments_29167f43-4683-4ef0-9fca-59c9d019cdf4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0975546c-5282-4482-b2e5-803cc664e66c" xlink:to="loc_us-gaap_ShortTermInvestments_29167f43-4683-4ef0-9fca-59c9d019cdf4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_8ad757f7-6931-49a3-950e-4f4a0b2de160" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0975546c-5282-4482-b2e5-803cc664e66c" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_8ad757f7-6931-49a3-950e-4f4a0b2de160" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_f4202b33-c9e6-4717-af3f-c114bef63a34" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0975546c-5282-4482-b2e5-803cc664e66c" xlink:to="loc_us-gaap_DerivativeLiabilities_f4202b33-c9e6-4717-af3f-c114bef63a34" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_83b15c4a-7a17-4d59-9ea3-335e85f61fc4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0975546c-5282-4482-b2e5-803cc664e66c" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_83b15c4a-7a17-4d59-9ea3-335e85f61fc4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_f49cfbb3-0f39-4a52-8d86-572c15d1b122" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_83b15c4a-7a17-4d59-9ea3-335e85f61fc4" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_f49cfbb3-0f39-4a52-8d86-572c15d1b122" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_f49cfbb3-0f39-4a52-8d86-572c15d1b122_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_f49cfbb3-0f39-4a52-8d86-572c15d1b122" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_f49cfbb3-0f39-4a52-8d86-572c15d1b122_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_715d3bc1-ceaa-468e-a65f-00b1913ed05e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_f49cfbb3-0f39-4a52-8d86-572c15d1b122" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_715d3bc1-ceaa-468e-a65f-00b1913ed05e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_8bf0fd8f-b967-4148-ab7f-215de6f80c85" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_715d3bc1-ceaa-468e-a65f-00b1913ed05e" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_8bf0fd8f-b967-4148-ab7f-215de6f80c85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsNonrecurringMember_fa3540dd-8644-49b3-a5a9-31f51dbdc2ce" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsNonrecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_715d3bc1-ceaa-468e-a65f-00b1913ed05e" xlink:to="loc_us-gaap_FairValueMeasurementsNonrecurringMember_fa3540dd-8644-49b3-a5a9-31f51dbdc2ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9e5db80b-186d-4017-ad2a-d535bb7b143a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_83b15c4a-7a17-4d59-9ea3-335e85f61fc4" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9e5db80b-186d-4017-ad2a-d535bb7b143a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9e5db80b-186d-4017-ad2a-d535bb7b143a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9e5db80b-186d-4017-ad2a-d535bb7b143a" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9e5db80b-186d-4017-ad2a-d535bb7b143a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e1f1d357-2589-4f11-86e4-2137d1d58275" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9e5db80b-186d-4017-ad2a-d535bb7b143a" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e1f1d357-2589-4f11-86e4-2137d1d58275" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_029a0fc5-02da-4a50-b677-86a84f59c146" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e1f1d357-2589-4f11-86e4-2137d1d58275" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_029a0fc5-02da-4a50-b677-86a84f59c146" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_51458d5b-10c6-4dee-bf2c-591fa48ea297" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e1f1d357-2589-4f11-86e4-2137d1d58275" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_51458d5b-10c6-4dee-bf2c-591fa48ea297" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_bdd213f6-2335-476b-b05d-397fc70bd331" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e1f1d357-2589-4f11-86e4-2137d1d58275" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_bdd213f6-2335-476b-b05d-397fc70bd331" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_ae26e128-3e68-43bb-a730-591108259c79" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_83b15c4a-7a17-4d59-9ea3-335e85f61fc4" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_ae26e128-3e68-43bb-a730-591108259c79" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_ae26e128-3e68-43bb-a730-591108259c79_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_ae26e128-3e68-43bb-a730-591108259c79" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_ae26e128-3e68-43bb-a730-591108259c79_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_d9b6bb19-3abc-4616-a0ec-d449eb27d1da" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_ae26e128-3e68-43bb-a730-591108259c79" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_d9b6bb19-3abc-4616-a0ec-d449eb27d1da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCapMember_cb4b5716-595c-43fa-8c57-3bcadbf8dbaf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateCapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_d9b6bb19-3abc-4616-a0ec-d449eb27d1da" xlink:to="loc_us-gaap_InterestRateCapMember_cb4b5716-595c-43fa-8c57-3bcadbf8dbaf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_68d7ea91-a606-4a89-8428-a24852c05ce0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_d9b6bb19-3abc-4616-a0ec-d449eb27d1da" xlink:to="loc_us-gaap_InterestRateSwapMember_68d7ea91-a606-4a89-8428-a24852c05ce0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_d0c85a4a-9c96-49f1-beba-5bd818aab399" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_83b15c4a-7a17-4d59-9ea3-335e85f61fc4" xlink:to="loc_us-gaap_FinancialInstrumentAxis_d0c85a4a-9c96-49f1-beba-5bd818aab399" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_d0c85a4a-9c96-49f1-beba-5bd818aab399_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_d0c85a4a-9c96-49f1-beba-5bd818aab399" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_d0c85a4a-9c96-49f1-beba-5bd818aab399_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_acc4d583-6368-4ebd-96a3-0f5032b5d0cb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_d0c85a4a-9c96-49f1-beba-5bd818aab399" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_acc4d583-6368-4ebd-96a3-0f5032b5d0cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_fa5246e0-0013-4605-abf5-c63425d07904" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_acc4d583-6368-4ebd-96a3-0f5032b5d0cb" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_fa5246e0-0013-4605-abf5-c63425d07904" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_92a0b85e-a207-471d-aeed-a938567a746b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_acc4d583-6368-4ebd-96a3-0f5032b5d0cb" xlink:to="loc_us-gaap_MoneyMarketFundsMember_92a0b85e-a207-471d-aeed-a938567a746b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_daac74f7-7e57-4aad-85cc-c685ea184b67" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_acc4d583-6368-4ebd-96a3-0f5032b5d0cb" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_daac74f7-7e57-4aad-85cc-c685ea184b67" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_f5c5b21b-6146-41e5-b395-728280306a6e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_acc4d583-6368-4ebd-96a3-0f5032b5d0cb" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_f5c5b21b-6146-41e5-b395-728280306a6e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ForwardStartingInterestRateSwapMember_36a09581-f838-4a40-a3e7-8e235b184a1f" xlink:href="zi-20201231.xsd#zi_ForwardStartingInterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_acc4d583-6368-4ebd-96a3-0f5032b5d0cb" xlink:to="loc_zi_ForwardStartingInterestRateSwapMember_36a09581-f838-4a40-a3e7-8e235b184a1f" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/CommitmentandContingencies" xlink:type="simple" xlink:href="zi-20201231.xsd#CommitmentandContingencies"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/CommitmentandContingencies" xlink:type="extended" id="ia7a24f76a537437693ee161871be91fb_CommitmentandContingencies"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/CommitmentandContingenciesTables" xlink:type="simple" xlink:href="zi-20201231.xsd#CommitmentandContingenciesTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/CommitmentandContingenciesTables" xlink:type="extended" id="i137abe96fde74bce8dd7f0c383d66804_CommitmentandContingenciesTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/CommitmentandContingenciesDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#CommitmentandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/CommitmentandContingenciesDetails" xlink:type="extended" id="icea281b891294cb88c9498629e621ac7_CommitmentandContingenciesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_f6947153-a42f-4745-a260-e2420cf77607" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationPenaltiesAccrued_592da7b5-b422-4ae9-b236-08a791d5c585" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExaminationPenaltiesAccrued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f6947153-a42f-4745-a260-e2420cf77607" xlink:to="loc_us-gaap_IncomeTaxExaminationPenaltiesAccrued_592da7b5-b422-4ae9-b236-08a791d5c585" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_86b13666-cc37-4ed1-99c6-f2284d1ab4ee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f6947153-a42f-4745-a260-e2420cf77607" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_86b13666-cc37-4ed1-99c6-f2284d1ab4ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_50fd20db-1390-43cb-a2f4-0e7662e39ae8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f6947153-a42f-4745-a260-e2420cf77607" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_50fd20db-1390-43cb-a2f4-0e7662e39ae8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_d15b0d5f-e4cc-4168-8aa3-af5a53e36b2b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_50fd20db-1390-43cb-a2f4-0e7662e39ae8" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_d15b0d5f-e4cc-4168-8aa3-af5a53e36b2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d15b0d5f-e4cc-4168-8aa3-af5a53e36b2b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d15b0d5f-e4cc-4168-8aa3-af5a53e36b2b" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d15b0d5f-e4cc-4168-8aa3-af5a53e36b2b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2fad36c6-beee-4dbf-908a-2143cbf87840" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d15b0d5f-e4cc-4168-8aa3-af5a53e36b2b" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2fad36c6-beee-4dbf-908a-2143cbf87840" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_KomikoLTDMember_6581171c-142e-4426-acf2-6c7c4f2a94b7" xlink:href="zi-20201231.xsd#zi_KomikoLTDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2fad36c6-beee-4dbf-908a-2143cbf87840" xlink:to="loc_zi_KomikoLTDMember_6581171c-142e-4426-acf2-6c7c4f2a94b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreAcquisitionZoomInformationIncMember_d450957b-6772-402a-b60e-d273d31aca54" xlink:href="zi-20201231.xsd#zi_PreAcquisitionZoomInformationIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2fad36c6-beee-4dbf-908a-2143cbf87840" xlink:to="loc_zi_PreAcquisitionZoomInformationIncMember_d450957b-6772-402a-b60e-d273d31aca54" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/StockholdersEquityandMembersDeficit" xlink:type="simple" xlink:href="zi-20201231.xsd#StockholdersEquityandMembersDeficit"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/StockholdersEquityandMembersDeficit" xlink:type="extended" id="i341512cfecc049bc9c86ae1a18b78590_StockholdersEquityandMembersDeficit"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/StockholdersEquityandMembersDeficitDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#StockholdersEquityandMembersDeficitDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/StockholdersEquityandMembersDeficitDetails" xlink:type="extended" id="ifa8422ee143448b3ab19a3594e5cc2d9_StockholdersEquityandMembersDeficitDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_a61b6d6d-178c-40f6-9ef0-cef1e4370762" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_CommonStockNumberOfVotesPerShareHeld_08079f97-7de7-49c7-a4c9-dcd180840018" xlink:href="zi-20201231.xsd#zi_CommonStockNumberOfVotesPerShareHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_a61b6d6d-178c-40f6-9ef0-cef1e4370762" xlink:to="loc_zi_CommonStockNumberOfVotesPerShareHeld_08079f97-7de7-49c7-a4c9-dcd180840018" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PercentOfClassBAndClassCAsOutstandingCommonStockVotingRights_ff6688b3-8f7e-4cae-b599-e3da74e81773" xlink:href="zi-20201231.xsd#zi_PercentOfClassBAndClassCAsOutstandingCommonStockVotingRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_a61b6d6d-178c-40f6-9ef0-cef1e4370762" xlink:to="loc_zi_PercentOfClassBAndClassCAsOutstandingCommonStockVotingRights_ff6688b3-8f7e-4cae-b599-e3da74e81773" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ConversionRatioToClassACommonStock_b54b5ce8-1aee-46a2-9a6e-46c6f4db2236" xlink:href="zi-20201231.xsd#zi_ConversionRatioToClassACommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_a61b6d6d-178c-40f6-9ef0-cef1e4370762" xlink:to="loc_zi_ConversionRatioToClassACommonStock_b54b5ce8-1aee-46a2-9a6e-46c6f4db2236" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PercentOfClassBAndClassCAsOutstandingCommonStockConversionRights_3be6f6b9-9703-42da-971b-0015b415430e" xlink:href="zi-20201231.xsd#zi_PercentOfClassBAndClassCAsOutstandingCommonStockConversionRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_a61b6d6d-178c-40f6-9ef0-cef1e4370762" xlink:to="loc_zi_PercentOfClassBAndClassCAsOutstandingCommonStockConversionRights_3be6f6b9-9703-42da-971b-0015b415430e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_4942dbce-634e-4927-b338-84d76b2f75b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_a61b6d6d-178c-40f6-9ef0-cef1e4370762" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_4942dbce-634e-4927-b338-84d76b2f75b9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_04a472b2-f5a4-4a1e-a558-e81cf4a31c5f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_4942dbce-634e-4927-b338-84d76b2f75b9" xlink:to="loc_us-gaap_StatementClassOfStockAxis_04a472b2-f5a4-4a1e-a558-e81cf4a31c5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_04a472b2-f5a4-4a1e-a558-e81cf4a31c5f_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_04a472b2-f5a4-4a1e-a558-e81cf4a31c5f" xlink:to="loc_us-gaap_ClassOfStockDomain_04a472b2-f5a4-4a1e-a558-e81cf4a31c5f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a80591b4-cd4b-495d-9cbd-bb57c2f848ee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_04a472b2-f5a4-4a1e-a558-e81cf4a31c5f" xlink:to="loc_us-gaap_ClassOfStockDomain_a80591b4-cd4b-495d-9cbd-bb57c2f848ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_71353caf-efb3-498c-ade0-0e8be90fc644" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a80591b4-cd4b-495d-9cbd-bb57c2f848ee" xlink:to="loc_us-gaap_CommonClassAMember_71353caf-efb3-498c-ade0-0e8be90fc644" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_934d2c08-41a0-4465-9bb0-3ffeb8abd4d9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a80591b4-cd4b-495d-9cbd-bb57c2f848ee" xlink:to="loc_us-gaap_CommonClassBMember_934d2c08-41a0-4465-9bb0-3ffeb8abd4d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_35376c21-1580-4dda-84fa-0920f8c636ab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a80591b4-cd4b-495d-9cbd-bb57c2f848ee" xlink:to="loc_us-gaap_CommonClassCMember_35376c21-1580-4dda-84fa-0920f8c636ab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_a96577b6-c8c1-41fc-a3cb-a9e19a2e9deb" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_4942dbce-634e-4927-b338-84d76b2f75b9" xlink:to="loc_srt_RangeAxis_a96577b6-c8c1-41fc-a3cb-a9e19a2e9deb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a96577b6-c8c1-41fc-a3cb-a9e19a2e9deb_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_a96577b6-c8c1-41fc-a3cb-a9e19a2e9deb" xlink:to="loc_srt_RangeMember_a96577b6-c8c1-41fc-a3cb-a9e19a2e9deb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6eb49b6c-bc5b-4400-8d73-28a6999527b4" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_a96577b6-c8c1-41fc-a3cb-a9e19a2e9deb" xlink:to="loc_srt_RangeMember_6eb49b6c-bc5b-4400-8d73-28a6999527b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_54a45f88-eb36-4e71-a58f-724aa9e525b1" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_6eb49b6c-bc5b-4400-8d73-28a6999527b4" xlink:to="loc_srt_MinimumMember_54a45f88-eb36-4e71-a58f-724aa9e525b1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_120cbee2-6539-4fe2-9f68-a62e2c36b77d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_6eb49b6c-bc5b-4400-8d73-28a6999527b4" xlink:to="loc_srt_MaximumMember_120cbee2-6539-4fe2-9f68-a62e2c36b77d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_58f1c746-f732-47f1-8fd9-aab0d9140c03" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_4942dbce-634e-4927-b338-84d76b2f75b9" xlink:to="loc_us-gaap_AwardTypeAxis_58f1c746-f732-47f1-8fd9-aab0d9140c03" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_58f1c746-f732-47f1-8fd9-aab0d9140c03_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_58f1c746-f732-47f1-8fd9-aab0d9140c03" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_58f1c746-f732-47f1-8fd9-aab0d9140c03_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7243b33c-fa09-4574-955b-91a6d2b66a41" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_58f1c746-f732-47f1-8fd9-aab0d9140c03" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7243b33c-fa09-4574-955b-91a6d2b66a41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_OpCoUnitsMember_1bdb3434-0d04-4dc9-8cdd-ab98b886e63f" xlink:href="zi-20201231.xsd#zi_OpCoUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7243b33c-fa09-4574-955b-91a6d2b66a41" xlink:to="loc_zi_OpCoUnitsMember_1bdb3434-0d04-4dc9-8cdd-ab98b886e63f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_HoldCoUnitsMember_213671bc-0042-473a-b356-67f174b35fef" xlink:href="zi-20201231.xsd#zi_HoldCoUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7243b33c-fa09-4574-955b-91a6d2b66a41" xlink:to="loc_zi_HoldCoUnitsMember_213671bc-0042-473a-b356-67f174b35fef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestLineItems_706ef379-200a-4248-9041-6290e55b8a80" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterestLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedBalanceShares_62cbef9d-d37f-4f7c-a5f3-9639b4f8dc6a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentOwnedBalanceShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_706ef379-200a-4248-9041-6290e55b8a80" xlink:to="loc_us-gaap_InvestmentOwnedBalanceShares_62cbef9d-d37f-4f7c-a5f3-9639b4f8dc6a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_7faea149-e9a1-47c8-9586-e341e97b2bcc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_706ef379-200a-4248-9041-6290e55b8a80" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_7faea149-e9a1-47c8-9586-e341e97b2bcc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestTable_fd9e64b3-be90-4559-a48d-0334de18a5ff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterestTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MinorityInterestLineItems_706ef379-200a-4248-9041-6290e55b8a80" xlink:to="loc_us-gaap_MinorityInterestTable_fd9e64b3-be90-4559-a48d-0334de18a5ff" xlink:type="arc" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_5f7398fb-2743-43ca-801f-6c29f75ea354" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_fd9e64b3-be90-4559-a48d-0334de18a5ff" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_5f7398fb-2743-43ca-801f-6c29f75ea354" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_5f7398fb-2743-43ca-801f-6c29f75ea354_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_5f7398fb-2743-43ca-801f-6c29f75ea354" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_5f7398fb-2743-43ca-801f-6c29f75ea354_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_49ec0676-0b37-4a78-97d5-7ed35ce0a984" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_5f7398fb-2743-43ca-801f-6c29f75ea354" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_49ec0676-0b37-4a78-97d5-7ed35ce0a984" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ZoomInfoHoldCoMember_8755c5da-0ade-4dee-9228-6de424e3fd0c" xlink:href="zi-20201231.xsd#zi_ZoomInfoHoldCoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_49ec0676-0b37-4a78-97d5-7ed35ce0a984" xlink:to="loc_zi_ZoomInfoHoldCoMember_8755c5da-0ade-4dee-9228-6de424e3fd0c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ZoomInfoOpCoMember_c10ff599-c605-46c3-81f1-4c5387b1c35d" xlink:href="zi-20201231.xsd#zi_ZoomInfoOpCoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_49ec0676-0b37-4a78-97d5-7ed35ce0a984" xlink:to="loc_zi_ZoomInfoOpCoMember_c10ff599-c605-46c3-81f1-4c5387b1c35d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_3a278212-93d9-46a2-810b-5ef4747c8b12" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_fd9e64b3-be90-4559-a48d-0334de18a5ff" xlink:to="loc_dei_LegalEntityAxis_3a278212-93d9-46a2-810b-5ef4747c8b12" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_3a278212-93d9-46a2-810b-5ef4747c8b12_default" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_3a278212-93d9-46a2-810b-5ef4747c8b12" xlink:to="loc_dei_EntityDomain_3a278212-93d9-46a2-810b-5ef4747c8b12_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_6074d838-5d8a-4384-bfe4-565f81eb1d1a" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_3a278212-93d9-46a2-810b-5ef4747c8b12" xlink:to="loc_dei_EntityDomain_6074d838-5d8a-4384-bfe4-565f81eb1d1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ZoomInfoHoldCoMember_063b26e4-18e8-424a-a3ec-b8bf63246f7f" xlink:href="zi-20201231.xsd#zi_ZoomInfoHoldCoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_6074d838-5d8a-4384-bfe4-565f81eb1d1a" xlink:to="loc_zi_ZoomInfoHoldCoMember_063b26e4-18e8-424a-a3ec-b8bf63246f7f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/RedeemableSeriesAPreferredUnits" xlink:type="simple" xlink:href="zi-20201231.xsd#RedeemableSeriesAPreferredUnits"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/RedeemableSeriesAPreferredUnits" xlink:type="extended" id="i3ce7c4126e704a338f6afe32df9e3e48_RedeemableSeriesAPreferredUnits"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/RedeemableSeriesAPreferredUnitsDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#RedeemableSeriesAPreferredUnitsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/RedeemableSeriesAPreferredUnitsDetails" xlink:type="extended" id="i15961663bf2b47be90cc57774f729ee3_RedeemableSeriesAPreferredUnitsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued_ab93a34b-c136-4646-b560-2457c080757c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:to="loc_us-gaap_PreferredStockSharesIssued_ab93a34b-c136-4646-b560-2457c080757c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquity_7b7448cc-f23f-47e7-a1c2-481a63c88a82" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:to="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquity_7b7448cc-f23f-47e7-a1c2-481a63c88a82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfStockIssuanceCosts_787985ec-3e90-4389-b8b9-8422b4abd3bf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfStockIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:to="loc_us-gaap_PaymentsOfStockIssuanceCosts_787985ec-3e90-4389-b8b9-8422b4abd3bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_a213b6fa-02f9-4e3b-b1ee-fc3c2f3c29a9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_a213b6fa-02f9-4e3b-b1ee-fc3c2f3c29a9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_TemporaryEquityRedeemedAndCancelledDuringPeriodValue_ae6e107d-fa06-41b5-990e-c269922cdef8" xlink:href="zi-20201231.xsd#zi_TemporaryEquityRedeemedAndCancelledDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:to="loc_zi_TemporaryEquityRedeemedAndCancelledDuringPeriodValue_ae6e107d-fa06-41b5-990e-c269922cdef8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockAccretionOfRedemptionDiscount_cb5c897c-773a-4256-b774-634db6b0af50" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockAccretionOfRedemptionDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:to="loc_us-gaap_PreferredStockAccretionOfRedemptionDiscount_cb5c897c-773a-4256-b774-634db6b0af50" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_f3866b64-72f7-476d-a0ee-9e60b05d67c8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_f3866b64-72f7-476d-a0ee-9e60b05d67c8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityAccretionOfDividends_256c3a5d-4266-4d3f-ab00-62bfa61cfe64" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquityAccretionOfDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:to="loc_us-gaap_TemporaryEquityAccretionOfDividends_256c3a5d-4266-4d3f-ab00-62bfa61cfe64" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_TemporaryEquityExcessDueUponEarlyRedemption_6ed7966e-b55b-4ccb-83b4-51fd7a1e9fae" xlink:href="zi-20201231.xsd#zi_TemporaryEquityExcessDueUponEarlyRedemption"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:to="loc_zi_TemporaryEquityExcessDueUponEarlyRedemption_6ed7966e-b55b-4ccb-83b4-51fd7a1e9fae" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_TemporaryEquityExcessDueUponEarlyRedemptionNoncontrollingInterests_b7c3d9af-de7d-4509-86e5-c02d0645ea8e" xlink:href="zi-20201231.xsd#zi_TemporaryEquityExcessDueUponEarlyRedemptionNoncontrollingInterests"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:to="loc_zi_TemporaryEquityExcessDueUponEarlyRedemptionNoncontrollingInterests_b7c3d9af-de7d-4509-86e5-c02d0645ea8e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_TemporaryEquityExcessDueUponEarlyRedemptionCommonStock_d87b73bd-f221-4e25-a973-7f51168302df" xlink:href="zi-20201231.xsd#zi_TemporaryEquityExcessDueUponEarlyRedemptionCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:to="loc_zi_TemporaryEquityExcessDueUponEarlyRedemptionCommonStock_d87b73bd-f221-4e25-a973-7f51168302df" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_d7840988-aefd-4592-99fc-9eeff8c5e516" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_fa6ca052-8a0c-4d31-a941-5785fc569920" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_d7840988-aefd-4592-99fc-9eeff8c5e516" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_fc7cb54f-b69a-4c2f-8fc0-bfa6041c528d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_d7840988-aefd-4592-99fc-9eeff8c5e516" xlink:to="loc_us-gaap_StatementClassOfStockAxis_fc7cb54f-b69a-4c2f-8fc0-bfa6041c528d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_fc7cb54f-b69a-4c2f-8fc0-bfa6041c528d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_fc7cb54f-b69a-4c2f-8fc0-bfa6041c528d" xlink:to="loc_us-gaap_ClassOfStockDomain_fc7cb54f-b69a-4c2f-8fc0-bfa6041c528d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_05c30469-c1d5-45d9-b6bd-be13a7f6afb0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_fc7cb54f-b69a-4c2f-8fc0-bfa6041c528d" xlink:to="loc_us-gaap_ClassOfStockDomain_05c30469-c1d5-45d9-b6bd-be13a7f6afb0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_RedeemableSeriesAPreferredUnitsMember_4bdf6722-3315-4a66-ba6d-d16a74a6df68" xlink:href="zi-20201231.xsd#zi_RedeemableSeriesAPreferredUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_05c30469-c1d5-45d9-b6bd-be13a7f6afb0" xlink:to="loc_zi_RedeemableSeriesAPreferredUnitsMember_4bdf6722-3315-4a66-ba6d-d16a74a6df68" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_303a440e-5162-4a79-9499-c32e636bbff7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_d7840988-aefd-4592-99fc-9eeff8c5e516" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_303a440e-5162-4a79-9499-c32e636bbff7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_303a440e-5162-4a79-9499-c32e636bbff7_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_303a440e-5162-4a79-9499-c32e636bbff7" xlink:to="loc_us-gaap_EquityComponentDomain_303a440e-5162-4a79-9499-c32e636bbff7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_84091d80-9b18-4b36-b7f6-36a7e811ace6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_303a440e-5162-4a79-9499-c32e636bbff7" xlink:to="loc_us-gaap_EquityComponentDomain_84091d80-9b18-4b36-b7f6-36a7e811ace6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_f5b1987a-c05c-4f30-b62b-402669d94375" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_84091d80-9b18-4b36-b7f6-36a7e811ace6" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_f5b1987a-c05c-4f30-b62b-402669d94375" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EarningsPerShare" xlink:type="simple" xlink:href="zi-20201231.xsd#EarningsPerShare"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EarningsPerShare" xlink:type="extended" id="i143201faeb824e9991cfd8dd4b0d0e9e_EarningsPerShare"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EarningsPerShareTables" xlink:type="simple" xlink:href="zi-20201231.xsd#EarningsPerShareTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EarningsPerShareTables" xlink:type="extended" id="i7989f88e2e654f55b69b7594ed30443b_EarningsPerShareTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EarningsPerShareBasicandDilutedNetLossPerShareDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#EarningsPerShareBasicandDilutedNetLossPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EarningsPerShareBasicandDilutedNetLossPerShareDetails" xlink:type="extended" id="ibed536c9f8004d9aa295dc5f0fa213c4_EarningsPerShareBasicandDilutedNetLossPerShareDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicLineItems_723ae955-ce6d-4ead-9dab-6e0171fe125d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareBasicLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_4a90b4eb-affe-49b8-903e-3077e9e4e63d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_723ae955-ce6d-4ead-9dab-6e0171fe125d" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_4a90b4eb-affe-49b8-903e-3077e9e4e63d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UndistributedEarningsLossAvailableToCommonShareholdersBasic_10209bb9-6ef4-432c-b4da-f9dc2f1fecaf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UndistributedEarningsLossAvailableToCommonShareholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_4a90b4eb-affe-49b8-903e-3077e9e4e63d" xlink:to="loc_us-gaap_UndistributedEarningsLossAvailableToCommonShareholdersBasic_10209bb9-6ef4-432c-b4da-f9dc2f1fecaf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_f2ef27d2-1f21-4ea8-b938-d1db7d22cb7a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_4a90b4eb-affe-49b8-903e-3077e9e4e63d" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_f2ef27d2-1f21-4ea8-b938-d1db7d22cb7a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_b80a1114-564b-457f-80aa-67e4c40ad854" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_4a90b4eb-affe-49b8-903e-3077e9e4e63d" xlink:to="loc_us-gaap_EarningsPerShareBasic_b80a1114-564b-457f-80aa-67e4c40ad854" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_bc7b4ef8-e85d-4f5a-8632-1c3cc73d086c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_723ae955-ce6d-4ead-9dab-6e0171fe125d" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_bc7b4ef8-e85d-4f5a-8632-1c3cc73d086c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UndistributedEarningsLossAvailableToCommonShareholdersBasic_07640078-f0bc-468e-ad31-54bad47ee73b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UndistributedEarningsLossAvailableToCommonShareholdersBasic"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_UndistributedEarningsDilutedIncreaseDecreaseInEarningsUponConversionOfPotentiallyDilutiveInstruments_61f313a7-251e-405c-a745-c314a3417d64" xlink:href="zi-20201231.xsd#zi_UndistributedEarningsDilutedIncreaseDecreaseInEarningsUponConversionOfPotentiallyDilutiveInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_bc7b4ef8-e85d-4f5a-8632-1c3cc73d086c" xlink:to="loc_zi_UndistributedEarningsDilutedIncreaseDecreaseInEarningsUponConversionOfPotentiallyDilutiveInstruments_61f313a7-251e-405c-a745-c314a3417d64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_UndistributedEarningsDilutedReallocationOfEarningsUponConversionOfPotentiallyDilutiveInstruments_96eb0d03-fe5b-4ad4-abd2-9d51d4bec470" xlink:href="zi-20201231.xsd#zi_UndistributedEarningsDilutedReallocationOfEarningsUponConversionOfPotentiallyDilutiveInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_bc7b4ef8-e85d-4f5a-8632-1c3cc73d086c" xlink:to="loc_zi_UndistributedEarningsDilutedReallocationOfEarningsUponConversionOfPotentiallyDilutiveInstruments_96eb0d03-fe5b-4ad4-abd2-9d51d4bec470" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_UndistributedEarningsDilutedReallocationOfEarningsUponConversionOfCommonStock_b6a4a0aa-5e02-4e5c-a87b-e72fcc2139dd" xlink:href="zi-20201231.xsd#zi_UndistributedEarningsDilutedReallocationOfEarningsUponConversionOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_bc7b4ef8-e85d-4f5a-8632-1c3cc73d086c" xlink:to="loc_zi_UndistributedEarningsDilutedReallocationOfEarningsUponConversionOfCommonStock_b6a4a0aa-5e02-4e5c-a87b-e72fcc2139dd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UndistributedEarningsLossAvailableToCommonShareholdersDiluted_c3e53122-d1ba-418a-aa56-680de4938dd2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UndistributedEarningsLossAvailableToCommonShareholdersDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_bc7b4ef8-e85d-4f5a-8632-1c3cc73d086c" xlink:to="loc_us-gaap_UndistributedEarningsLossAvailableToCommonShareholdersDiluted_c3e53122-d1ba-418a-aa56-680de4938dd2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_2d201b70-a625-411a-ae81-8691ef4bece4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_2e87d89f-e32e-417a-adc3-164c6a76641f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_bc7b4ef8-e85d-4f5a-8632-1c3cc73d086c" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_2e87d89f-e32e-417a-adc3-164c6a76641f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_IncrementalCommonSharesAttributableToDilutiveEffectOfConversionOfCommonStock_1f97c1a7-644c-4c26-8a5c-e79eb6284fc5" xlink:href="zi-20201231.xsd#zi_IncrementalCommonSharesAttributableToDilutiveEffectOfConversionOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_bc7b4ef8-e85d-4f5a-8632-1c3cc73d086c" xlink:to="loc_zi_IncrementalCommonSharesAttributableToDilutiveEffectOfConversionOfCommonStock_1f97c1a7-644c-4c26-8a5c-e79eb6284fc5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_3b2d763c-b2fd-4978-8a90-67d963c1afc6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_bc7b4ef8-e85d-4f5a-8632-1c3cc73d086c" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_3b2d763c-b2fd-4978-8a90-67d963c1afc6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_4dccd4a0-ec56-4d7f-8fcc-1a76a22fc450" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_bc7b4ef8-e85d-4f5a-8632-1c3cc73d086c" xlink:to="loc_us-gaap_EarningsPerShareDiluted_4dccd4a0-ec56-4d7f-8fcc-1a76a22fc450" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_0f91714d-0da8-4a68-bd7a-b67e22b94d1e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_723ae955-ce6d-4ead-9dab-6e0171fe125d" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_0f91714d-0da8-4a68-bd7a-b67e22b94d1e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_a40044d2-632d-4a34-b931-e953ee5e9dc9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_0f91714d-0da8-4a68-bd7a-b67e22b94d1e" xlink:to="loc_us-gaap_StatementClassOfStockAxis_a40044d2-632d-4a34-b931-e953ee5e9dc9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a40044d2-632d-4a34-b931-e953ee5e9dc9_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a40044d2-632d-4a34-b931-e953ee5e9dc9" xlink:to="loc_us-gaap_ClassOfStockDomain_a40044d2-632d-4a34-b931-e953ee5e9dc9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_df4a8697-20bf-446c-a542-da1d1d86429b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a40044d2-632d-4a34-b931-e953ee5e9dc9" xlink:to="loc_us-gaap_ClassOfStockDomain_df4a8697-20bf-446c-a542-da1d1d86429b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_046047e5-e675-4718-8434-02806ee3efe5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_df4a8697-20bf-446c-a542-da1d1d86429b" xlink:to="loc_us-gaap_CommonClassAMember_046047e5-e675-4718-8434-02806ee3efe5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_20b0a0ec-21c0-4b20-a599-3d9b9f5d962e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_df4a8697-20bf-446c-a542-da1d1d86429b" xlink:to="loc_us-gaap_CommonClassCMember_20b0a0ec-21c0-4b20-a599-3d9b9f5d962e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_1fe4ae72-d262-4e1f-afd8-93257a77b130" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_0f91714d-0da8-4a68-bd7a-b67e22b94d1e" xlink:to="loc_us-gaap_AwardTypeAxis_1fe4ae72-d262-4e1f-afd8-93257a77b130" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1fe4ae72-d262-4e1f-afd8-93257a77b130_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_1fe4ae72-d262-4e1f-afd8-93257a77b130" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1fe4ae72-d262-4e1f-afd8-93257a77b130_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4df94468-f746-44b0-a4dd-3a9504033b48" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_1fe4ae72-d262-4e1f-afd8-93257a77b130" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4df94468-f746-44b0-a4dd-3a9504033b48" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_HSKBIClass1UnitsMember_06363c14-a8be-433d-84c7-61bc8db8da25" xlink:href="zi-20201231.xsd#zi_HSKBIClass1UnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4df94468-f746-44b0-a4dd-3a9504033b48" xlink:to="loc_zi_HSKBIClass1UnitsMember_06363c14-a8be-433d-84c7-61bc8db8da25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ClassPUnitsMember_5591a27a-b747-4a54-9242-4d4bcb67882d" xlink:href="zi-20201231.xsd#zi_ClassPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4df94468-f746-44b0-a4dd-3a9504033b48" xlink:to="loc_zi_ClassPUnitsMember_5591a27a-b747-4a54-9242-4d4bcb67882d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_7f9b9d52-c120-48fb-b393-f51b72682837" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4df94468-f746-44b0-a4dd-3a9504033b48" xlink:to="loc_us-gaap_EmployeeStockOptionMember_7f9b9d52-c120-48fb-b393-f51b72682837" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EarningsPerSharePotentialCommonStockEquivalentsExcludedfromCalculationofDilutedNetLossPerShareDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#EarningsPerSharePotentialCommonStockEquivalentsExcludedfromCalculationofDilutedNetLossPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EarningsPerSharePotentialCommonStockEquivalentsExcludedfromCalculationofDilutedNetLossPerShareDetails" xlink:type="extended" id="i1689f3cb3ddb4aacb2824876b5077da9_EarningsPerSharePotentialCommonStockEquivalentsExcludedfromCalculationofDilutedNetLossPerShareDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_108797fc-35fd-4847-bb90-30dd045462e1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_9846063b-2c4a-4662-a260-5803f291ee05" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_108797fc-35fd-4847-bb90-30dd045462e1" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_9846063b-2c4a-4662-a260-5803f291ee05" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_c5df1eab-7aac-4ec0-8534-e6b436c1a873" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_108797fc-35fd-4847-bb90-30dd045462e1" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_c5df1eab-7aac-4ec0-8534-e6b436c1a873" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_e2fe7f6f-3156-4636-935e-4387eb4e66a2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_c5df1eab-7aac-4ec0-8534-e6b436c1a873" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_e2fe7f6f-3156-4636-935e-4387eb4e66a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e2fe7f6f-3156-4636-935e-4387eb4e66a2_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_e2fe7f6f-3156-4636-935e-4387eb4e66a2" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e2fe7f6f-3156-4636-935e-4387eb4e66a2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_93d0a891-b7b1-4efd-ae1e-8142dffb64c4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_e2fe7f6f-3156-4636-935e-4387eb4e66a2" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_93d0a891-b7b1-4efd-ae1e-8142dffb64c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_OpCoUnitsMember_14d465ec-9e57-426c-8d8a-c66447cecf2c" xlink:href="zi-20201231.xsd#zi_OpCoUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_93d0a891-b7b1-4efd-ae1e-8142dffb64c4" xlink:to="loc_zi_OpCoUnitsMember_14d465ec-9e57-426c-8d8a-c66447cecf2c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_f5e4c619-00b4-4b68-9c61-b11a8152fbb1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_93d0a891-b7b1-4efd-ae1e-8142dffb64c4" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_f5e4c619-00b4-4b68-9c61-b11a8152fbb1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PhantomShareUnitsPSUsMember_1a37c8f9-a91b-40d8-871d-e657c303e038" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PhantomShareUnitsPSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_93d0a891-b7b1-4efd-ae1e-8142dffb64c4" xlink:to="loc_us-gaap_PhantomShareUnitsPSUsMember_1a37c8f9-a91b-40d8-871d-e657c303e038" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_LTIPUnitsMember_0dfa30e4-a229-4e95-9676-4b21093b1c55" xlink:href="zi-20201231.xsd#zi_LTIPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_93d0a891-b7b1-4efd-ae1e-8142dffb64c4" xlink:to="loc_zi_LTIPUnitsMember_0dfa30e4-a229-4e95-9676-4b21093b1c55" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_HoldCoUnitsMember_6b59d48f-d213-4711-ace8-afdc20c16e8c" xlink:href="zi-20201231.xsd#zi_HoldCoUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_93d0a891-b7b1-4efd-ae1e-8142dffb64c4" xlink:to="loc_zi_HoldCoUnitsMember_6b59d48f-d213-4711-ace8-afdc20c16e8c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_HSKBIIClass1UnitsMember_6a20b875-b54a-42db-bf17-5ae54d3b9f48" xlink:href="zi-20201231.xsd#zi_HSKBIIClass1UnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_93d0a891-b7b1-4efd-ae1e-8142dffb64c4" xlink:to="loc_zi_HSKBIIClass1UnitsMember_6a20b875-b54a-42db-bf17-5ae54d3b9f48" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/Leases" xlink:type="simple" xlink:href="zi-20201231.xsd#Leases"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/Leases" xlink:type="extended" id="ie016596765734267a8e583c11337e7d2_Leases"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/LeasesTables" xlink:type="simple" xlink:href="zi-20201231.xsd#LeasesTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/LeasesTables" xlink:type="extended" id="i319ab2ee2a8043f8a6c155f55275c6cd_LeasesTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#LeasesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/LeasesNarrativeDetails" xlink:type="extended" id="i9f40fa59f8c9446ab342b6b22e51ead5_LeasesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_c452c8a1-a481-48d6-a830-b8b25ee59822" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_LessorOperatingLeaseRemainingSubleaseTerm_0a520729-ba32-41f7-8a49-a179610b23eb" xlink:href="zi-20201231.xsd#zi_LessorOperatingLeaseRemainingSubleaseTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_c452c8a1-a481-48d6-a830-b8b25ee59822" xlink:to="loc_zi_LessorOperatingLeaseRemainingSubleaseTerm_0a520729-ba32-41f7-8a49-a179610b23eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseExpense_6f472af6-14b7-4e13-8f65-2e6974b684f3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_c452c8a1-a481-48d6-a830-b8b25ee59822" xlink:to="loc_us-gaap_OperatingLeaseExpense_6f472af6-14b7-4e13-8f65-2e6974b684f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_992b8101-f39c-4c6b-a923-cdc6f19a93a9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_c452c8a1-a481-48d6-a830-b8b25ee59822" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_992b8101-f39c-4c6b-a923-cdc6f19a93a9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_9bf99a8c-1a8d-4002-ab4e-0b0bd37c655c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_992b8101-f39c-4c6b-a923-cdc6f19a93a9" xlink:to="loc_srt_RangeAxis_9bf99a8c-1a8d-4002-ab4e-0b0bd37c655c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_9bf99a8c-1a8d-4002-ab4e-0b0bd37c655c_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_9bf99a8c-1a8d-4002-ab4e-0b0bd37c655c" xlink:to="loc_srt_RangeMember_9bf99a8c-1a8d-4002-ab4e-0b0bd37c655c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_8df65a69-0c99-4e17-a175-a461a0187e75" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_9bf99a8c-1a8d-4002-ab4e-0b0bd37c655c" xlink:to="loc_srt_RangeMember_8df65a69-0c99-4e17-a175-a461a0187e75" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_4091d8bb-7b78-4476-b015-85212fa8473e" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_8df65a69-0c99-4e17-a175-a461a0187e75" xlink:to="loc_srt_MinimumMember_4091d8bb-7b78-4476-b015-85212fa8473e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_b503ea03-1e7f-4d93-bfe0-eb62532da31c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_8df65a69-0c99-4e17-a175-a461a0187e75" xlink:to="loc_srt_MaximumMember_b503ea03-1e7f-4d93-bfe0-eb62532da31c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/LeasesAdditionalDetailsRelatedtoLeasesRecordedontheBalanceSheetDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#LeasesAdditionalDetailsRelatedtoLeasesRecordedontheBalanceSheetDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/LeasesAdditionalDetailsRelatedtoLeasesRecordedontheBalanceSheetDetails" xlink:type="extended" id="ifffa7c964d80456da953ac18c7b7d8fd_LeasesAdditionalDetailsRelatedtoLeasesRecordedontheBalanceSheetDetails"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/LeasesOtherInformationRelatedtoLeasesDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#LeasesOtherInformationRelatedtoLeasesDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/LeasesOtherInformationRelatedtoLeasesDetails" xlink:type="extended" id="i23d51b57441c467a98893ed03259b4ca_LeasesOtherInformationRelatedtoLeasesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_2989794f-d1d8-4df9-9d14-04457423b931" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments_4e86d7a0-98b5-44da-954b-32f5a17d2cdb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2989794f-d1d8-4df9-9d14-04457423b931" xlink:to="loc_us-gaap_OperatingLeasePayments_4e86d7a0-98b5-44da-954b-32f5a17d2cdb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_86360969-20b5-4bee-a525-0b01f4c6cf4c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2989794f-d1d8-4df9-9d14-04457423b931" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_86360969-20b5-4bee-a525-0b01f4c6cf4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiabilityAndAdjustments_cfefe188-fe45-465d-92fa-fca9daf8a641" xlink:href="zi-20201231.xsd#zi_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiabilityAndAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2989794f-d1d8-4df9-9d14-04457423b931" xlink:to="loc_zi_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiabilityAndAdjustments_cfefe188-fe45-465d-92fa-fca9daf8a641" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_c984624a-f7ad-4d89-aeb6-acc378514985" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2989794f-d1d8-4df9-9d14-04457423b931" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_c984624a-f7ad-4d89-aeb6-acc378514985" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_e9483eb8-52b4-46e6-9cc5-fb9e1c21fc71" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2989794f-d1d8-4df9-9d14-04457423b931" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_e9483eb8-52b4-46e6-9cc5-fb9e1c21fc71" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_45f92076-793c-44e3-b464-cf0fe7d8ce95" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2989794f-d1d8-4df9-9d14-04457423b931" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_45f92076-793c-44e3-b464-cf0fe7d8ce95" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_6b4f5e5c-ed29-462c-b006-641a5162fa0a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_45f92076-793c-44e3-b464-cf0fe7d8ce95" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_6b4f5e5c-ed29-462c-b006-641a5162fa0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6b4f5e5c-ed29-462c-b006-641a5162fa0a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6b4f5e5c-ed29-462c-b006-641a5162fa0a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6b4f5e5c-ed29-462c-b006-641a5162fa0a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ac601044-46ec-40c1-96b0-a5b888f2d1eb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6b4f5e5c-ed29-462c-b006-641a5162fa0a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ac601044-46ec-40c1-96b0-a5b888f2d1eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreAcquisitionZoomInformationIncMember_5f812e98-e32b-4054-bc2e-4c11abf4fbf9" xlink:href="zi-20201231.xsd#zi_PreAcquisitionZoomInformationIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ac601044-46ec-40c1-96b0-a5b888f2d1eb" xlink:to="loc_zi_PreAcquisitionZoomInformationIncMember_5f812e98-e32b-4054-bc2e-4c11abf4fbf9" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/LeasesUndiscountedFutureMinimumPaymentsUnderNonCancellableLeasesDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#LeasesUndiscountedFutureMinimumPaymentsUnderNonCancellableLeasesDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/LeasesUndiscountedFutureMinimumPaymentsUnderNonCancellableLeasesDetails" xlink:type="extended" id="i43a8fb20dea24c0aae85c96f8d33bfd3_LeasesUndiscountedFutureMinimumPaymentsUnderNonCancellableLeasesDetails"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensation" xlink:type="simple" xlink:href="zi-20201231.xsd#EquitybasedCompensation"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensation" xlink:type="extended" id="iaadec02ec709474baf837055a29589c5_EquitybasedCompensation"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationTables" xlink:type="simple" xlink:href="zi-20201231.xsd#EquitybasedCompensationTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationTables" xlink:type="extended" id="icf03d619dfe745d1a7721c8ab750be51_EquitybasedCompensationTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#EquitybasedCompensationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationNarrativeDetails" xlink:type="extended" id="ic41c79df860c4780bd963bfc8f5b8c1d_EquitybasedCompensationNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_978a327d-2cd3-4a88-b54f-018164241f15" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_978a327d-2cd3-4a88-b54f-018164241f15" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseToAuthorizedSharesBasedOnStockOutstandingPercentage_d6cd90b4-72fc-4bc3-a76b-0a683a12695f" xlink:href="zi-20201231.xsd#zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseToAuthorizedSharesBasedOnStockOutstandingPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseToAuthorizedSharesBasedOnStockOutstandingPercentage_d6cd90b4-72fc-4bc3-a76b-0a683a12695f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardStockAwardConversionIncrementalGrantDateFairValue_6b6cab71-9f02-44f4-b924-68a86b21ace9" xlink:href="zi-20201231.xsd#zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardStockAwardConversionIncrementalGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardStockAwardConversionIncrementalGrantDateFairValue_6b6cab71-9f02-44f4-b924-68a86b21ace9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_16a21256-53c4-4e1d-960f-9181ec380564" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_16a21256-53c4-4e1d-960f-9181ec380564" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_6a95ac8c-fda5-4c4a-bddd-76bd982e1310" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_6a95ac8c-fda5-4c4a-bddd-76bd982e1310" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_92538da5-c9a3-4829-afe3-4ba76b8ab1b4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_92538da5-c9a3-4829-afe3-4ba76b8ab1b4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_ccbf2e64-e3e3-4ece-894c-b9d24793573d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_ccbf2e64-e3e3-4ece-894c-b9d24793573d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockSharesConverted1_7fbf0f13-99b4-464c-850f-5219c3b66e92" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockSharesConverted1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_ConversionOfStockSharesConverted1_7fbf0f13-99b4-464c-850f-5219c3b66e92" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockSharesIssued1_cf58dd76-a5d7-4d7c-826a-a2ba8c3bf8b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockSharesIssued1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_ConversionOfStockSharesIssued1_cf58dd76-a5d7-4d7c-826a-a2ba8c3bf8b7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_210b422a-dd7f-4558-832b-53f9fda40058" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_210b422a-dd7f-4558-832b-53f9fda40058" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEconomicEquivalentOfAwardGrantedShares_c24d8b47-9e79-4c9b-9461-ca173cda5622" xlink:href="zi-20201231.xsd#zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEconomicEquivalentOfAwardGrantedShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEconomicEquivalentOfAwardGrantedShares_c24d8b47-9e79-4c9b-9461-ca173cda5622" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformanceVestingConditionPercentage_92aec41a-a777-4bf7-bcad-a35bdb56d7f1" xlink:href="zi-20201231.xsd#zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformanceVestingConditionPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformanceVestingConditionPercentage_92aec41a-a777-4bf7-bcad-a35bdb56d7f1" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ModificationToShareBasedCompensationArrangementNumberOfGranteesAffected_e908f661-aba2-4a2b-95f8-a1059702dfee" xlink:href="zi-20201231.xsd#zi_ModificationToShareBasedCompensationArrangementNumberOfGranteesAffected"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_zi_ModificationToShareBasedCompensationArrangementNumberOfGranteesAffected_e908f661-aba2-4a2b-95f8-a1059702dfee" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ShareBasedPaymentArrangementNonvestedAwardExcludingOptionCostNotYetRecognizedAmountIncreaseDecrease_abadd619-fad8-4b73-8a0b-0c87f14ed3e8" xlink:href="zi-20201231.xsd#zi_ShareBasedPaymentArrangementNonvestedAwardExcludingOptionCostNotYetRecognizedAmountIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_zi_ShareBasedPaymentArrangementNonvestedAwardExcludingOptionCostNotYetRecognizedAmountIncreaseDecrease_abadd619-fad8-4b73-8a0b-0c87f14ed3e8" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_CapitalAllocatedForFutureDistribution_17d56978-b5a9-45e3-b3ec-247a1f5509e3" xlink:href="zi-20201231.xsd#zi_CapitalAllocatedForFutureDistribution"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_zi_CapitalAllocatedForFutureDistribution_17d56978-b5a9-45e3-b3ec-247a1f5509e3" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_CapitalAllocatedForFutureDistributionDistributionTerm_3653ecee-2aac-40bf-b237-0a2cc638e6a1" xlink:href="zi-20201231.xsd#zi_CapitalAllocatedForFutureDistributionDistributionTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_zi_CapitalAllocatedForFutureDistributionDistributionTerm_3653ecee-2aac-40bf-b237-0a2cc638e6a1" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfCapitalDistribution_f0fa87bb-a1e7-4e63-9ba3-45c3373a590e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfCapitalDistribution"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_PaymentsOfCapitalDistribution_f0fa87bb-a1e7-4e63-9ba3-45c3373a590e" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_2257ac97-e194-4841-b6a6-a8d9d16abb29" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_2257ac97-e194-4841-b6a6-a8d9d16abb29" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_f1b3d084-7c48-410b-9443-f25a5f249a95" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_f1b3d084-7c48-410b-9443-f25a5f249a95" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ShareBasedCompensationByShareBasedPaymentAwardPeriodToSettleAwards_47f233a0-b74b-4cc4-b3c6-b718b593f108" xlink:href="zi-20201231.xsd#zi_ShareBasedCompensationByShareBasedPaymentAwardPeriodToSettleAwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_zi_ShareBasedCompensationByShareBasedPaymentAwardPeriodToSettleAwards_47f233a0-b74b-4cc4-b3c6-b718b593f108" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAcceleratedVestingNumber_aacd34a8-8f12-4252-b0b7-a6e7298b2a74" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAcceleratedVestingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAcceleratedVestingNumber_aacd34a8-8f12-4252-b0b7-a6e7298b2a74" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_65b39bf2-828e-44ef-b384-d4b955c0680c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_65b39bf2-828e-44ef-b384-d4b955c0680c" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_c54c3392-22f8-40e9-bfd0-925179674bd4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_c54c3392-22f8-40e9-bfd0-925179674bd4" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_bebab1dc-0c84-4271-903b-411aafa7db59" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_bebab1dc-0c84-4271-903b-411aafa7db59" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_40b6e3de-2f9a-4a60-809f-240f906c398a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_40b6e3de-2f9a-4a60-809f-240f906c398a" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_244e8e11-8a50-45cf-8afd-c4e00ff860ba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dee88483-e5c9-4ca1-984a-88ad3ed54438" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_244e8e11-8a50-45cf-8afd-c4e00ff860ba" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_cc7fc792-650c-4dc0-b54e-470ebe52f7b0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_244e8e11-8a50-45cf-8afd-c4e00ff860ba" xlink:to="loc_us-gaap_AwardTypeAxis_cc7fc792-650c-4dc0-b54e-470ebe52f7b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cc7fc792-650c-4dc0-b54e-470ebe52f7b0_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_cc7fc792-650c-4dc0-b54e-470ebe52f7b0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cc7fc792-650c-4dc0-b54e-470ebe52f7b0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_012f3f3b-5dd5-4dc9-91ec-7a3505018d00" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_cc7fc792-650c-4dc0-b54e-470ebe52f7b0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_012f3f3b-5dd5-4dc9-91ec-7a3505018d00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreIPOAwardsMember_740b8981-521a-45cb-91f3-b9c09208e386" xlink:href="zi-20201231.xsd#zi_PreIPOAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_012f3f3b-5dd5-4dc9-91ec-7a3505018d00" xlink:to="loc_zi_PreIPOAwardsMember_740b8981-521a-45cb-91f3-b9c09208e386" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PostIPOAwardsMember_3b044d47-402a-487e-bdc9-38812906c05f" xlink:href="zi-20201231.xsd#zi_PostIPOAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_012f3f3b-5dd5-4dc9-91ec-7a3505018d00" xlink:to="loc_zi_PostIPOAwardsMember_3b044d47-402a-487e-bdc9-38812906c05f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_bf4a7fe6-afca-4ceb-9612-b5d87cc4581b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_012f3f3b-5dd5-4dc9-91ec-7a3505018d00" xlink:to="loc_us-gaap_EmployeeStockOptionMember_bf4a7fe6-afca-4ceb-9612-b5d87cc4581b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_HoldCoUnitsMember_3794d0ec-3b37-4c67-af66-54e40025f879" xlink:href="zi-20201231.xsd#zi_HoldCoUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_012f3f3b-5dd5-4dc9-91ec-7a3505018d00" xlink:to="loc_zi_HoldCoUnitsMember_3794d0ec-3b37-4c67-af66-54e40025f879" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ClassPUnitsMember_c6168b61-ca81-4f05-afa7-06b7c2fbf7fd" xlink:href="zi-20201231.xsd#zi_ClassPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_012f3f3b-5dd5-4dc9-91ec-7a3505018d00" xlink:to="loc_zi_ClassPUnitsMember_c6168b61-ca81-4f05-afa7-06b7c2fbf7fd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_IncentiveUnitsMember_e3043ca4-7c2c-4f86-a745-86fa2594a8d6" xlink:href="zi-20201231.xsd#zi_IncentiveUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_012f3f3b-5dd5-4dc9-91ec-7a3505018d00" xlink:to="loc_zi_IncentiveUnitsMember_e3043ca4-7c2c-4f86-a745-86fa2594a8d6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PhantomUnitsMember_7ee948e7-c7df-493d-8a5c-60c6e1ce3d36" xlink:href="zi-20201231.xsd#zi_PhantomUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_012f3f3b-5dd5-4dc9-91ec-7a3505018d00" xlink:to="loc_zi_PhantomUnitsMember_7ee948e7-c7df-493d-8a5c-60c6e1ce3d36" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_OpCoUnitsMember_1728408d-23b0-4cc4-a8cf-21139a6b146e" xlink:href="zi-20201231.xsd#zi_OpCoUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_012f3f3b-5dd5-4dc9-91ec-7a3505018d00" xlink:to="loc_zi_OpCoUnitsMember_1728408d-23b0-4cc4-a8cf-21139a6b146e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_Class1UnitMember_cec20da6-0a17-4d14-ac4b-a38d5fd9a9f7" xlink:href="zi-20201231.xsd#zi_Class1UnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_012f3f3b-5dd5-4dc9-91ec-7a3505018d00" xlink:to="loc_zi_Class1UnitMember_cec20da6-0a17-4d14-ac4b-a38d5fd9a9f7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_26f712f1-b3ba-4431-a2d6-97a81115b6d3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_244e8e11-8a50-45cf-8afd-c4e00ff860ba" xlink:to="loc_us-gaap_PlanNameAxis_26f712f1-b3ba-4431-a2d6-97a81115b6d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_26f712f1-b3ba-4431-a2d6-97a81115b6d3_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_26f712f1-b3ba-4431-a2d6-97a81115b6d3" xlink:to="loc_us-gaap_PlanNameDomain_26f712f1-b3ba-4431-a2d6-97a81115b6d3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_238b63ad-5e3d-405c-9542-4d806f318429" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_26f712f1-b3ba-4431-a2d6-97a81115b6d3" xlink:to="loc_us-gaap_PlanNameDomain_238b63ad-5e3d-405c-9542-4d806f318429" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_OmnibusIncentivePlan2020Member_45e70e8f-fb58-4bba-a958-8ad40f2c2856" xlink:href="zi-20201231.xsd#zi_OmnibusIncentivePlan2020Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_238b63ad-5e3d-405c-9542-4d806f318429" xlink:to="loc_zi_OmnibusIncentivePlan2020Member_45e70e8f-fb58-4bba-a958-8ad40f2c2856" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_A2019PhantomUnitPlanMember_9e5f9a00-743b-4e65-a846-1628a01008cd" xlink:href="zi-20201231.xsd#zi_A2019PhantomUnitPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_238b63ad-5e3d-405c-9542-4d806f318429" xlink:to="loc_zi_A2019PhantomUnitPlanMember_9e5f9a00-743b-4e65-a846-1628a01008cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_00905c0a-8f65-4b41-9587-2f495f5d61c6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_244e8e11-8a50-45cf-8afd-c4e00ff860ba" xlink:to="loc_us-gaap_VestingAxis_00905c0a-8f65-4b41-9587-2f495f5d61c6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_00905c0a-8f65-4b41-9587-2f495f5d61c6_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_00905c0a-8f65-4b41-9587-2f495f5d61c6" xlink:to="loc_us-gaap_VestingDomain_00905c0a-8f65-4b41-9587-2f495f5d61c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_e2e0f5c0-f125-4924-a02f-8f93de50c6e9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_00905c0a-8f65-4b41-9587-2f495f5d61c6" xlink:to="loc_us-gaap_VestingDomain_e2e0f5c0-f125-4924-a02f-8f93de50c6e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_5c43a371-34c9-452a-913f-ce79de25567f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_e2e0f5c0-f125-4924-a02f-8f93de50c6e9" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_5c43a371-34c9-452a-913f-ce79de25567f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_96ce06f3-fcfe-4e5a-8b39-98f92f1e7432" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_e2e0f5c0-f125-4924-a02f-8f93de50c6e9" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_96ce06f3-fcfe-4e5a-8b39-98f92f1e7432" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_84d43527-ab18-4325-ab4f-b40685f81dac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_244e8e11-8a50-45cf-8afd-c4e00ff860ba" xlink:to="loc_us-gaap_StatementClassOfStockAxis_84d43527-ab18-4325-ab4f-b40685f81dac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_84d43527-ab18-4325-ab4f-b40685f81dac_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_84d43527-ab18-4325-ab4f-b40685f81dac" xlink:to="loc_us-gaap_ClassOfStockDomain_84d43527-ab18-4325-ab4f-b40685f81dac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a27d6fe5-b869-41de-bcf2-313ea31f974e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_84d43527-ab18-4325-ab4f-b40685f81dac" xlink:to="loc_us-gaap_ClassOfStockDomain_a27d6fe5-b869-41de-bcf2-313ea31f974e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_10d6b7c1-07b7-4ca6-8c5d-3eb92d43e7f0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a27d6fe5-b869-41de-bcf2-313ea31f974e" xlink:to="loc_us-gaap_CommonClassAMember_10d6b7c1-07b7-4ca6-8c5d-3eb92d43e7f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_CommonUnitsMember_d0bf0d1e-1541-4ea9-ae3e-a27ee34adacb" xlink:href="zi-20201231.xsd#zi_CommonUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a27d6fe5-b869-41de-bcf2-313ea31f974e" xlink:to="loc_zi_CommonUnitsMember_d0bf0d1e-1541-4ea9-ae3e-a27ee34adacb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_5f9ca695-6570-47b2-8286-ae0134b91e23" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_244e8e11-8a50-45cf-8afd-c4e00ff860ba" xlink:to="loc_srt_StatementScenarioAxis_5f9ca695-6570-47b2-8286-ae0134b91e23" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_5f9ca695-6570-47b2-8286-ae0134b91e23_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_5f9ca695-6570-47b2-8286-ae0134b91e23" xlink:to="loc_srt_ScenarioUnspecifiedDomain_5f9ca695-6570-47b2-8286-ae0134b91e23_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_53c35768-8fc9-415e-9e78-665663ad3ce4" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_5f9ca695-6570-47b2-8286-ae0134b91e23" xlink:to="loc_srt_ScenarioUnspecifiedDomain_53c35768-8fc9-415e-9e78-665663ad3ce4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_8c7bf152-a794-430d-a03f-7bb0837c2f4c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_53c35768-8fc9-415e-9e78-665663ad3ce4" xlink:to="loc_srt_ScenarioForecastMember_8c7bf152-a794-430d-a03f-7bb0837c2f4c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_2680558e-6c80-4304-ab1f-27d8de1b524d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_244e8e11-8a50-45cf-8afd-c4e00ff860ba" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_2680558e-6c80-4304-ab1f-27d8de1b524d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_2680558e-6c80-4304-ab1f-27d8de1b524d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_2680558e-6c80-4304-ab1f-27d8de1b524d" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_2680558e-6c80-4304-ab1f-27d8de1b524d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_de689bcf-b042-4967-a93d-dd43f2c34c6d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_2680558e-6c80-4304-ab1f-27d8de1b524d" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_de689bcf-b042-4967-a93d-dd43f2c34c6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IPOMember_65defa8a-ef2b-42d2-9749-a3a699d593d0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IPOMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_de689bcf-b042-4967-a93d-dd43f2c34c6d" xlink:to="loc_us-gaap_IPOMember_65defa8a-ef2b-42d2-9749-a3a699d593d0" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationRestrictedStockUnitsActivityDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#EquitybasedCompensationRestrictedStockUnitsActivityDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationRestrictedStockUnitsActivityDetails" xlink:type="extended" id="i136d26aa7045410ba05eb04ae28576ff_EquitybasedCompensationRestrictedStockUnitsActivityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1e9f1efd-b339-402e-9fcd-9554dbffbb29" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_435830f7-feb0-44f2-b540-077d6328397e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1e9f1efd-b339-402e-9fcd-9554dbffbb29" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_435830f7-feb0-44f2-b540-077d6328397e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_b7b3c63c-a21e-4805-bce9-ff98cf647afb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_435830f7-feb0-44f2-b540-077d6328397e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_b7b3c63c-a21e-4805-bce9-ff98cf647afb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0f1827dd-90f4-41f8-8c40-3865938df9f5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_435830f7-feb0-44f2-b540-077d6328397e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0f1827dd-90f4-41f8-8c40-3865938df9f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_ca8936b4-0af1-4995-af9b-a95a8028a30b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_435830f7-feb0-44f2-b540-077d6328397e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_ca8936b4-0af1-4995-af9b-a95a8028a30b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_1fdb7814-0c0d-4e28-8bc8-bcd92d3c9b08" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_435830f7-feb0-44f2-b540-077d6328397e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_1fdb7814-0c0d-4e28-8bc8-bcd92d3c9b08" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_645fc804-8f72-4aa1-a929-d42ff756ea2a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_df56caec-22b6-4b99-a248-a00b0cfeab7a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1e9f1efd-b339-402e-9fcd-9554dbffbb29" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_df56caec-22b6-4b99-a248-a00b0cfeab7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_3246f687-fcc2-485a-860d-26c8cbb5767c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_df56caec-22b6-4b99-a248-a00b0cfeab7a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_3246f687-fcc2-485a-860d-26c8cbb5767c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_38b8bc9d-2160-4e0d-ac6d-76088deb02f7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_df56caec-22b6-4b99-a248-a00b0cfeab7a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_38b8bc9d-2160-4e0d-ac6d-76088deb02f7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_ee51653d-5ede-451e-9a28-09e63b075ee5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_df56caec-22b6-4b99-a248-a00b0cfeab7a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_ee51653d-5ede-451e-9a28-09e63b075ee5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_2915b025-c034-42fc-a559-4479ce5e6682" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_df56caec-22b6-4b99-a248-a00b0cfeab7a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_2915b025-c034-42fc-a559-4479ce5e6682" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_2c6170fb-e388-484a-b1b1-b7c4921ef827" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_51554b95-9057-4959-b9bd-e97124b792f8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1e9f1efd-b339-402e-9fcd-9554dbffbb29" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_51554b95-9057-4959-b9bd-e97124b792f8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_45b6106c-1c4e-487c-b10a-a57b7d4e4d7c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_51554b95-9057-4959-b9bd-e97124b792f8" xlink:to="loc_us-gaap_AwardTypeAxis_45b6106c-1c4e-487c-b10a-a57b7d4e4d7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_45b6106c-1c4e-487c-b10a-a57b7d4e4d7c_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_45b6106c-1c4e-487c-b10a-a57b7d4e4d7c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_45b6106c-1c4e-487c-b10a-a57b7d4e4d7c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_77a1c3d5-2e3f-48f6-9a2f-baae013555e5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_45b6106c-1c4e-487c-b10a-a57b7d4e4d7c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_77a1c3d5-2e3f-48f6-9a2f-baae013555e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_f04a13eb-7a83-452f-9634-3f10159abe2b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_77a1c3d5-2e3f-48f6-9a2f-baae013555e5" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_f04a13eb-7a83-452f-9634-3f10159abe2b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationClassACommonStockOptionsActivityDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#EquitybasedCompensationClassACommonStockOptionsActivityDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationClassACommonStockOptionsActivityDetails" xlink:type="extended" id="id90d85cf54cf4210bb8af7119a2da540_EquitybasedCompensationClassACommonStockOptionsActivityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_008e369e-2bcf-4a5c-bc87-ae2f4850eaec" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_58320d70-f249-4d80-81f0-e26c6d5ede17" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_008e369e-2bcf-4a5c-bc87-ae2f4850eaec" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_58320d70-f249-4d80-81f0-e26c6d5ede17" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_7b6a25d4-8d9c-420b-acd3-653e958b376a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_58320d70-f249-4d80-81f0-e26c6d5ede17" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_7b6a25d4-8d9c-420b-acd3-653e958b376a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockSharesIssued1_8c5f32c5-d171-44cc-ace2-c779ddda6045" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockSharesIssued1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_58320d70-f249-4d80-81f0-e26c6d5ede17" xlink:to="loc_us-gaap_ConversionOfStockSharesIssued1_8c5f32c5-d171-44cc-ace2-c779ddda6045" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_1f7609ec-68f5-4ce3-9de0-737dc5faf6b5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_58320d70-f249-4d80-81f0-e26c6d5ede17" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_1f7609ec-68f5-4ce3-9de0-737dc5faf6b5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_0c72a308-b27e-483a-9735-7686699ca8f7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_7a3c5207-3de5-4ab8-8978-2a6b48cb5018" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_008e369e-2bcf-4a5c-bc87-ae2f4850eaec" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_7a3c5207-3de5-4ab8-8978-2a6b48cb5018" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_b9b2b5ab-7c16-4979-9563-046b5fba3196" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_7a3c5207-3de5-4ab8-8978-2a6b48cb5018" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_b9b2b5ab-7c16-4979-9563-046b5fba3196" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ConversionOfStockWeightedAverageGrantDateFairValue_b1e864f8-98ce-427d-bfc6-0ac98286fcc9" xlink:href="zi-20201231.xsd#zi_ConversionOfStockWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_7a3c5207-3de5-4ab8-8978-2a6b48cb5018" xlink:to="loc_zi_ConversionOfStockWeightedAverageGrantDateFairValue_b1e864f8-98ce-427d-bfc6-0ac98286fcc9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_cfadece3-7f8c-4310-915a-bd5be9d429e2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_7a3c5207-3de5-4ab8-8978-2a6b48cb5018" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_cfadece3-7f8c-4310-915a-bd5be9d429e2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_46b32576-45d6-4688-b1af-b7816925482d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_6c3ffacc-7957-4c60-8427-f8d7cf9b9055" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_008e369e-2bcf-4a5c-bc87-ae2f4850eaec" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_6c3ffacc-7957-4c60-8427-f8d7cf9b9055" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_733be2e2-d25a-400b-9ada-eba48008bdf1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_008e369e-2bcf-4a5c-bc87-ae2f4850eaec" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_733be2e2-d25a-400b-9ada-eba48008bdf1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_47deda02-6149-48a7-acb5-7511491c5c5d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_008e369e-2bcf-4a5c-bc87-ae2f4850eaec" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_47deda02-6149-48a7-acb5-7511491c5c5d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_a8e07a3f-1c3d-4f72-aa32-6068099b3f6b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_008e369e-2bcf-4a5c-bc87-ae2f4850eaec" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_a8e07a3f-1c3d-4f72-aa32-6068099b3f6b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c273ac3c-b322-4d6e-988d-3a0570bba760" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_008e369e-2bcf-4a5c-bc87-ae2f4850eaec" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c273ac3c-b322-4d6e-988d-3a0570bba760" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_a6ca93fc-04de-444b-950f-c0741d6439df" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c273ac3c-b322-4d6e-988d-3a0570bba760" xlink:to="loc_us-gaap_AwardTypeAxis_a6ca93fc-04de-444b-950f-c0741d6439df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a6ca93fc-04de-444b-950f-c0741d6439df_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_a6ca93fc-04de-444b-950f-c0741d6439df" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a6ca93fc-04de-444b-950f-c0741d6439df_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a71629b3-cbad-4bf5-ae66-7dc2713da17f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_a6ca93fc-04de-444b-950f-c0741d6439df" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a71629b3-cbad-4bf5-ae66-7dc2713da17f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_8d153a1f-7cf6-4ce4-878e-28e5659e92d3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a71629b3-cbad-4bf5-ae66-7dc2713da17f" xlink:to="loc_us-gaap_EmployeeStockOptionMember_8d153a1f-7cf6-4ce4-878e-28e5659e92d3" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationScheduleofValuationAssumptionsDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#EquitybasedCompensationScheduleofValuationAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationScheduleofValuationAssumptionsDetails" xlink:type="extended" id="i25110b83fe57481ca7fbd7108985a830_EquitybasedCompensationScheduleofValuationAssumptionsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate_41852757-3a83-47db-bf91-6f1c74627eac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate_41852757-3a83-47db-bf91-6f1c74627eac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_5e353d04-0efe-4cde-acfe-15692c9fb3cb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_5e353d04-0efe-4cde-acfe-15692c9fb3cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_4320748a-c48f-4a69-94c2-06168941e79d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_4320748a-c48f-4a69-94c2-06168941e79d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_d9eeeaaa-24be-4a23-8369-3c95b4d1c202" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_d9eeeaaa-24be-4a23-8369-3c95b4d1c202" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_c7204e7e-4020-4f15-bf1f-a9567948907d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_c7204e7e-4020-4f15-bf1f-a9567948907d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_9581b0c5-da19-4242-b8e1-54b0d3caf648" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_9581b0c5-da19-4242-b8e1-54b0d3caf648" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_179c5c27-055d-4aea-9de1-d5f9282d3cdd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_179c5c27-055d-4aea-9de1-d5f9282d3cdd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_MarketabilityDiscount_0b677c40-93dd-42ac-8b36-c794c18decae" xlink:href="zi-20201231.xsd#zi_MarketabilityDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:to="loc_zi_MarketabilityDiscount_0b677c40-93dd-42ac-8b36-c794c18decae" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_1a87bcc1-19e5-4ae9-94ee-90e3f11dcf56" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_1a87bcc1-19e5-4ae9-94ee-90e3f11dcf56" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_CommonUnitsPeriodUntilLiquidation_e20cce5e-dbce-4a11-8529-803fe0770531" xlink:href="zi-20201231.xsd#zi_CommonUnitsPeriodUntilLiquidation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:to="loc_zi_CommonUnitsPeriodUntilLiquidation_e20cce5e-dbce-4a11-8529-803fe0770531" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_WeightAppliedToIPOScenario_412d901f-5a34-46c1-833b-4a384a76f757" xlink:href="zi-20201231.xsd#zi_WeightAppliedToIPOScenario"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:to="loc_zi_WeightAppliedToIPOScenario_412d901f-5a34-46c1-833b-4a384a76f757" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_af269454-0897-447d-a4c4-6c94ad6bc2c8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_29a4361c-6f81-4bf2-9709-07051bb586fe" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_af269454-0897-447d-a4c4-6c94ad6bc2c8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_7b8f5555-0880-40da-87bf-20f0f87e9ac1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_af269454-0897-447d-a4c4-6c94ad6bc2c8" xlink:to="loc_us-gaap_AwardTypeAxis_7b8f5555-0880-40da-87bf-20f0f87e9ac1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7b8f5555-0880-40da-87bf-20f0f87e9ac1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_7b8f5555-0880-40da-87bf-20f0f87e9ac1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7b8f5555-0880-40da-87bf-20f0f87e9ac1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cc48feb5-9687-4240-8f4d-e922dcbbc40a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_7b8f5555-0880-40da-87bf-20f0f87e9ac1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cc48feb5-9687-4240-8f4d-e922dcbbc40a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_3e1070b0-97c4-4ef5-8e85-1b543b19cb50" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cc48feb5-9687-4240-8f4d-e922dcbbc40a" xlink:to="loc_us-gaap_EmployeeStockOptionMember_3e1070b0-97c4-4ef5-8e85-1b543b19cb50" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ClassPUnitsMember_c9760545-7712-4f22-a559-6c1810f55ef7" xlink:href="zi-20201231.xsd#zi_ClassPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cc48feb5-9687-4240-8f4d-e922dcbbc40a" xlink:to="loc_zi_ClassPUnitsMember_c9760545-7712-4f22-a559-6c1810f55ef7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_46605b29-1abe-4ad8-b537-30f0aae8787a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_af269454-0897-447d-a4c4-6c94ad6bc2c8" xlink:to="loc_us-gaap_PlanNameAxis_46605b29-1abe-4ad8-b537-30f0aae8787a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_46605b29-1abe-4ad8-b537-30f0aae8787a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_46605b29-1abe-4ad8-b537-30f0aae8787a" xlink:to="loc_us-gaap_PlanNameDomain_46605b29-1abe-4ad8-b537-30f0aae8787a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_83a64658-df1b-481e-a641-4b3765d42871" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_46605b29-1abe-4ad8-b537-30f0aae8787a" xlink:to="loc_us-gaap_PlanNameDomain_83a64658-df1b-481e-a641-4b3765d42871" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_EmployeeIncentiveProgramMember_820abbf9-b0e3-4294-a491-21cf1a881e6c" xlink:href="zi-20201231.xsd#zi_EmployeeIncentiveProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_83a64658-df1b-481e-a641-4b3765d42871" xlink:to="loc_zi_EmployeeIncentiveProgramMember_820abbf9-b0e3-4294-a491-21cf1a881e6c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_e0940e00-f60f-48f3-a67e-558d3f58a1cd" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_af269454-0897-447d-a4c4-6c94ad6bc2c8" xlink:to="loc_srt_RangeAxis_e0940e00-f60f-48f3-a67e-558d3f58a1cd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e0940e00-f60f-48f3-a67e-558d3f58a1cd_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_e0940e00-f60f-48f3-a67e-558d3f58a1cd" xlink:to="loc_srt_RangeMember_e0940e00-f60f-48f3-a67e-558d3f58a1cd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c3291137-efda-4f96-a3e1-be2be9793ea3" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_e0940e00-f60f-48f3-a67e-558d3f58a1cd" xlink:to="loc_srt_RangeMember_c3291137-efda-4f96-a3e1-be2be9793ea3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_48b549c4-868b-4d82-abee-d69496f49af8" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c3291137-efda-4f96-a3e1-be2be9793ea3" xlink:to="loc_srt_MinimumMember_48b549c4-868b-4d82-abee-d69496f49af8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_d5f0c1fc-e54c-4946-872e-a0b795d12f0b" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c3291137-efda-4f96-a3e1-be2be9793ea3" xlink:to="loc_srt_MaximumMember_d5f0c1fc-e54c-4946-872e-a0b795d12f0b" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationHoldCoUnitActivityDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#EquitybasedCompensationHoldCoUnitActivityDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationHoldCoUnitActivityDetails" xlink:type="extended" id="ib62dee33f5f24c27b1448b21b24a8576_EquitybasedCompensationHoldCoUnitActivityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a9670caf-34e5-414c-bd29-3434ba2b1900" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_bfd8a5e6-818f-4b01-88a7-2c008896e954" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a9670caf-34e5-414c-bd29-3434ba2b1900" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_bfd8a5e6-818f-4b01-88a7-2c008896e954" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_e66ce8dc-0e6c-467e-8782-60cd98abeff4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_bfd8a5e6-818f-4b01-88a7-2c008896e954" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_e66ce8dc-0e6c-467e-8782-60cd98abeff4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockSharesIssued1_099dd616-3df2-4940-9a5f-7a446991cf89" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockSharesIssued1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_bfd8a5e6-818f-4b01-88a7-2c008896e954" xlink:to="loc_us-gaap_ConversionOfStockSharesIssued1_099dd616-3df2-4940-9a5f-7a446991cf89" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_dfbb0895-da01-427c-9fb5-cd6ec12cbce3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_bfd8a5e6-818f-4b01-88a7-2c008896e954" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_dfbb0895-da01-427c-9fb5-cd6ec12cbce3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_1bda0d3c-8b5f-4957-99d2-0b45d22168f9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_bfd8a5e6-818f-4b01-88a7-2c008896e954" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_1bda0d3c-8b5f-4957-99d2-0b45d22168f9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_1a3b8d45-83b6-4695-b00c-14397f909f3d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_bfd8a5e6-818f-4b01-88a7-2c008896e954" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_1a3b8d45-83b6-4695-b00c-14397f909f3d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_aad2317b-6085-41c9-afab-ac17408ebacb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96efacc2-fd70-4440-b6e8-6d7deff256a7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a9670caf-34e5-414c-bd29-3434ba2b1900" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96efacc2-fd70-4440-b6e8-6d7deff256a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_ca647df7-41ab-4b27-ab4b-d15044674f06" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96efacc2-fd70-4440-b6e8-6d7deff256a7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_ca647df7-41ab-4b27-ab4b-d15044674f06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ConversionOfStockWeightedAverageGrantDateFairValue_9bde9b37-ffcc-43f6-b9e1-e96aaa913625" xlink:href="zi-20201231.xsd#zi_ConversionOfStockWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96efacc2-fd70-4440-b6e8-6d7deff256a7" xlink:to="loc_zi_ConversionOfStockWeightedAverageGrantDateFairValue_9bde9b37-ffcc-43f6-b9e1-e96aaa913625" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_5d3a9509-3b4d-42fa-8b9f-0aa9b9b4171b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96efacc2-fd70-4440-b6e8-6d7deff256a7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_5d3a9509-3b4d-42fa-8b9f-0aa9b9b4171b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_f2b91a19-ba69-4eb1-b8b1-4cc6ebd12e6c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96efacc2-fd70-4440-b6e8-6d7deff256a7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_f2b91a19-ba69-4eb1-b8b1-4cc6ebd12e6c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_d9d71f3b-b746-400d-ac2a-42290d4453f6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96efacc2-fd70-4440-b6e8-6d7deff256a7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_d9d71f3b-b746-400d-ac2a-42290d4453f6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_f456e881-b99b-49a4-a673-5a2909c72469" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_45d4ef99-3ec1-414e-aa9b-fc65fe106b0c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a9670caf-34e5-414c-bd29-3434ba2b1900" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_45d4ef99-3ec1-414e-aa9b-fc65fe106b0c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_56ac1eb0-acce-40a0-8be1-d421857e1fb2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_45d4ef99-3ec1-414e-aa9b-fc65fe106b0c" xlink:to="loc_us-gaap_AwardTypeAxis_56ac1eb0-acce-40a0-8be1-d421857e1fb2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_56ac1eb0-acce-40a0-8be1-d421857e1fb2_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_56ac1eb0-acce-40a0-8be1-d421857e1fb2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_56ac1eb0-acce-40a0-8be1-d421857e1fb2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_896e0544-5acc-4457-955c-8dc662871ee4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_56ac1eb0-acce-40a0-8be1-d421857e1fb2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_896e0544-5acc-4457-955c-8dc662871ee4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_HoldCoUnitsMember_52f49a52-fc7d-4f42-84ec-eedb48768f53" xlink:href="zi-20201231.xsd#zi_HoldCoUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_896e0544-5acc-4457-955c-8dc662871ee4" xlink:to="loc_zi_HoldCoUnitsMember_52f49a52-fc7d-4f42-84ec-eedb48768f53" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationOpCoUnitActivityDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#EquitybasedCompensationOpCoUnitActivityDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationOpCoUnitActivityDetails" xlink:type="extended" id="if4c99e497c604768b721d3442d12d83c_EquitybasedCompensationOpCoUnitActivityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dd26fe5c-4916-4670-bac9-9ff9d765b472" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f92da25e-a65d-4c76-88c7-743d71c9b6cc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dd26fe5c-4916-4670-bac9-9ff9d765b472" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f92da25e-a65d-4c76-88c7-743d71c9b6cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_08e93aa4-5a20-4681-b2ad-0d1c2b923de2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f92da25e-a65d-4c76-88c7-743d71c9b6cc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_08e93aa4-5a20-4681-b2ad-0d1c2b923de2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockSharesConverted1_446d5a34-d3ce-48e4-84df-c508dd682798" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockSharesConverted1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f92da25e-a65d-4c76-88c7-743d71c9b6cc" xlink:to="loc_us-gaap_ConversionOfStockSharesConverted1_446d5a34-d3ce-48e4-84df-c508dd682798" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_0d5826be-dd18-4434-a709-8e1e2fab888f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f92da25e-a65d-4c76-88c7-743d71c9b6cc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_0d5826be-dd18-4434-a709-8e1e2fab888f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_6233c5ee-5f9f-4f9d-b78d-fb85fbf322af" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f92da25e-a65d-4c76-88c7-743d71c9b6cc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_6233c5ee-5f9f-4f9d-b78d-fb85fbf322af" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_5e7edebb-d262-4288-909e-d2ed31715618" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c8fecde2-9c01-4562-94c1-2654f56e1e11" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dd26fe5c-4916-4670-bac9-9ff9d765b472" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c8fecde2-9c01-4562-94c1-2654f56e1e11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_d2f57407-5cde-4a9f-948d-ff676b936b67" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c8fecde2-9c01-4562-94c1-2654f56e1e11" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_d2f57407-5cde-4a9f-948d-ff676b936b67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ConversionOfStockWeightedAverageGrantDateFairValue_a6d32a61-1de4-46a5-b053-1a61d4da70f4" xlink:href="zi-20201231.xsd#zi_ConversionOfStockWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c8fecde2-9c01-4562-94c1-2654f56e1e11" xlink:to="loc_zi_ConversionOfStockWeightedAverageGrantDateFairValue_a6d32a61-1de4-46a5-b053-1a61d4da70f4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_69abec70-3857-49a0-8c32-1d4734eb423e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c8fecde2-9c01-4562-94c1-2654f56e1e11" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_69abec70-3857-49a0-8c32-1d4734eb423e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_82e27856-ed0d-40bb-aa35-aff24e862601" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c8fecde2-9c01-4562-94c1-2654f56e1e11" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_82e27856-ed0d-40bb-aa35-aff24e862601" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_22646ed9-ea6a-4b1e-9e31-d51422cabf2b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5800494c-2062-4c12-94bb-cd028467fa86" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dd26fe5c-4916-4670-bac9-9ff9d765b472" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5800494c-2062-4c12-94bb-cd028467fa86" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_e0fab707-c03c-4df1-933d-b509e16ec19a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5800494c-2062-4c12-94bb-cd028467fa86" xlink:to="loc_us-gaap_AwardTypeAxis_e0fab707-c03c-4df1-933d-b509e16ec19a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e0fab707-c03c-4df1-933d-b509e16ec19a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_e0fab707-c03c-4df1-933d-b509e16ec19a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e0fab707-c03c-4df1-933d-b509e16ec19a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4b0cd66a-317b-4c41-b4e2-6c4771ffb920" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_e0fab707-c03c-4df1-933d-b509e16ec19a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4b0cd66a-317b-4c41-b4e2-6c4771ffb920" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_OpCoUnitsMember_2fa382d7-50fc-4893-b2be-7e1c72389d7e" xlink:href="zi-20201231.xsd#zi_OpCoUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4b0cd66a-317b-4c41-b4e2-6c4771ffb920" xlink:to="loc_zi_OpCoUnitsMember_2fa382d7-50fc-4893-b2be-7e1c72389d7e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationClassPUnitsActivityDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#EquitybasedCompensationClassPUnitsActivityDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationClassPUnitsActivityDetails" xlink:type="extended" id="i60315e3e70bf419fb04e142da25b9f00_EquitybasedCompensationClassPUnitsActivityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7dbc182d-f93b-41bc-8d63-8b5ec5aae435" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7d61b042-4fd7-4527-b9aa-8c7c80531fad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7dbc182d-f93b-41bc-8d63-8b5ec5aae435" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7d61b042-4fd7-4527-b9aa-8c7c80531fad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_dad98872-0f47-4817-a2c3-641e71aa67c5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7d61b042-4fd7-4527-b9aa-8c7c80531fad" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_dad98872-0f47-4817-a2c3-641e71aa67c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockSharesConverted1_2ae12ce0-d17e-4380-aa4b-3bcafec3243c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockSharesConverted1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7d61b042-4fd7-4527-b9aa-8c7c80531fad" xlink:to="loc_us-gaap_ConversionOfStockSharesConverted1_2ae12ce0-d17e-4380-aa4b-3bcafec3243c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_6cefcf83-feb2-4ccc-83f8-b5d50081b99f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7d61b042-4fd7-4527-b9aa-8c7c80531fad" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_6cefcf83-feb2-4ccc-83f8-b5d50081b99f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_c9f80ba7-5d4e-4ad7-b064-55edc9e4833c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7d61b042-4fd7-4527-b9aa-8c7c80531fad" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_c9f80ba7-5d4e-4ad7-b064-55edc9e4833c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_519eeeb4-eaf4-4ff5-a405-d99d75165dcb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7d61b042-4fd7-4527-b9aa-8c7c80531fad" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_519eeeb4-eaf4-4ff5-a405-d99d75165dcb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_cb534f98-c474-4bf8-b6f9-a77c7e835826" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_6e1e7fa9-750b-45de-ab05-a3882110b850" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7dbc182d-f93b-41bc-8d63-8b5ec5aae435" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_6e1e7fa9-750b-45de-ab05-a3882110b850" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_e3e293b5-9f47-4720-badf-b93ced17d685" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_6e1e7fa9-750b-45de-ab05-a3882110b850" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_e3e293b5-9f47-4720-badf-b93ced17d685" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ConversionOfStockWeightedAverageGrantDateFairValue_8ccd1771-d082-4ebd-a2b7-2bf1c896be69" xlink:href="zi-20201231.xsd#zi_ConversionOfStockWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_6e1e7fa9-750b-45de-ab05-a3882110b850" xlink:to="loc_zi_ConversionOfStockWeightedAverageGrantDateFairValue_8ccd1771-d082-4ebd-a2b7-2bf1c896be69" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_470a2a66-2d90-4a72-81b2-9231e22a019a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_6e1e7fa9-750b-45de-ab05-a3882110b850" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_470a2a66-2d90-4a72-81b2-9231e22a019a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_fa9bc6cf-5105-4eb6-8134-9704baf6e19e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_6e1e7fa9-750b-45de-ab05-a3882110b850" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_fa9bc6cf-5105-4eb6-8134-9704baf6e19e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_c37d2451-d56e-4a8f-8e04-38564ee8db77" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_6e1e7fa9-750b-45de-ab05-a3882110b850" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_c37d2451-d56e-4a8f-8e04-38564ee8db77" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_597dd94a-092f-4891-a7a0-9119311f6a15" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f3eef674-1d90-4e67-a484-861962bf2e9a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7dbc182d-f93b-41bc-8d63-8b5ec5aae435" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f3eef674-1d90-4e67-a484-861962bf2e9a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_2e813581-f549-45c9-929f-57bd346eec3d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f3eef674-1d90-4e67-a484-861962bf2e9a" xlink:to="loc_us-gaap_AwardTypeAxis_2e813581-f549-45c9-929f-57bd346eec3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2e813581-f549-45c9-929f-57bd346eec3d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_2e813581-f549-45c9-929f-57bd346eec3d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2e813581-f549-45c9-929f-57bd346eec3d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f49ac7a0-edf3-43ab-9f9e-0bb5d9cdcdbd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_2e813581-f549-45c9-929f-57bd346eec3d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f49ac7a0-edf3-43ab-9f9e-0bb5d9cdcdbd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ClassPUnitsMember_4379f96b-2e6e-4123-9f45-96089ce9a67a" xlink:href="zi-20201231.xsd#zi_ClassPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f49ac7a0-edf3-43ab-9f9e-0bb5d9cdcdbd" xlink:to="loc_zi_ClassPUnitsMember_4379f96b-2e6e-4123-9f45-96089ce9a67a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationLTIPUnitsActivityDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#EquitybasedCompensationLTIPUnitsActivityDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationLTIPUnitsActivityDetails" xlink:type="extended" id="i9671a504aebf43fcb1c75ec01ddcc92e_EquitybasedCompensationLTIPUnitsActivityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0572fd16-c5f8-42eb-8f37-12a5a5195e70" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f505ab77-9c39-4199-bf2b-f0475763241d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0572fd16-c5f8-42eb-8f37-12a5a5195e70" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f505ab77-9c39-4199-bf2b-f0475763241d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_27155629-0dc2-49db-8d30-7bfe51c0bca4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f505ab77-9c39-4199-bf2b-f0475763241d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_27155629-0dc2-49db-8d30-7bfe51c0bca4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0f98b8db-8f19-4a33-be25-c48717aaba00" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f505ab77-9c39-4199-bf2b-f0475763241d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0f98b8db-8f19-4a33-be25-c48717aaba00" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_86f53b1a-c402-486f-8c6c-74df14e8ae54" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_7ec78e63-cbaf-4be7-b475-7bf17d86baef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0572fd16-c5f8-42eb-8f37-12a5a5195e70" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_7ec78e63-cbaf-4be7-b475-7bf17d86baef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_8fa30656-f59a-4ec8-b85c-970a7e90134c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_7ec78e63-cbaf-4be7-b475-7bf17d86baef" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_8fa30656-f59a-4ec8-b85c-970a7e90134c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_903f67f8-d7d1-406f-bbbd-29f872ea6f15" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_7ec78e63-cbaf-4be7-b475-7bf17d86baef" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_903f67f8-d7d1-406f-bbbd-29f872ea6f15" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_847abd4b-74f6-4fdb-be2a-4e1cf0313b15" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a31b0b51-5759-442b-80e7-a056033e082d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0572fd16-c5f8-42eb-8f37-12a5a5195e70" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a31b0b51-5759-442b-80e7-a056033e082d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_cc06b7d8-99bd-4909-8853-0bc757b85d5e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a31b0b51-5759-442b-80e7-a056033e082d" xlink:to="loc_us-gaap_AwardTypeAxis_cc06b7d8-99bd-4909-8853-0bc757b85d5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cc06b7d8-99bd-4909-8853-0bc757b85d5e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_cc06b7d8-99bd-4909-8853-0bc757b85d5e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cc06b7d8-99bd-4909-8853-0bc757b85d5e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_54bd631a-36a8-4240-ad02-970365d2e5b0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_cc06b7d8-99bd-4909-8853-0bc757b85d5e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_54bd631a-36a8-4240-ad02-970365d2e5b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_LTIPUnitsMember_153f103b-19fc-4541-a3fa-e0c554d9c697" xlink:href="zi-20201231.xsd#zi_LTIPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_54bd631a-36a8-4240-ad02-970365d2e5b0" xlink:to="loc_zi_LTIPUnitsMember_153f103b-19fc-4541-a3fa-e0c554d9c697" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationEquitybasedCompensationExpenseandSummaryofUnamortizedEquityBasedCompensationCostsDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#EquitybasedCompensationEquitybasedCompensationExpenseandSummaryofUnamortizedEquityBasedCompensationCostsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationEquitybasedCompensationExpenseandSummaryofUnamortizedEquityBasedCompensationCostsDetails" xlink:type="extended" id="i6ce8b5c09a5942db98b67e6bba2ef5d3_EquitybasedCompensationEquitybasedCompensationExpenseandSummaryofUnamortizedEquityBasedCompensationCostsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a434d742-18e4-4177-b3bd-7626954ef5d3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_6ab586cc-57fd-4ed5-bba9-1f62b2d4223c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a434d742-18e4-4177-b3bd-7626954ef5d3" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_6ab586cc-57fd-4ed5-bba9-1f62b2d4223c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_93ff0bdb-67b0-4d52-9851-259db8b3a16a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a434d742-18e4-4177-b3bd-7626954ef5d3" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_93ff0bdb-67b0-4d52-9851-259db8b3a16a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_dcee6c5e-37c6-450a-9f8e-f788f352f573" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a434d742-18e4-4177-b3bd-7626954ef5d3" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_dcee6c5e-37c6-450a-9f8e-f788f352f573" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_74db856d-ff6b-46f9-82ad-ebe6e70b4137" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a434d742-18e4-4177-b3bd-7626954ef5d3" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_74db856d-ff6b-46f9-82ad-ebe6e70b4137" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_83e9b991-6c29-4364-b5cd-52cd61398c28" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a434d742-18e4-4177-b3bd-7626954ef5d3" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_83e9b991-6c29-4364-b5cd-52cd61398c28" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5dae550f-ea2c-4f56-9f13-b77b8e682321" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a434d742-18e4-4177-b3bd-7626954ef5d3" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5dae550f-ea2c-4f56-9f13-b77b8e682321" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_5bf63156-542a-4897-a433-50eacf8bc88d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5dae550f-ea2c-4f56-9f13-b77b8e682321" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_5bf63156-542a-4897-a433-50eacf8bc88d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_5bf63156-542a-4897-a433-50eacf8bc88d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_5bf63156-542a-4897-a433-50eacf8bc88d" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_5bf63156-542a-4897-a433-50eacf8bc88d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_dfa0d86a-ad63-4710-bd21-961b8aff33b6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_5bf63156-542a-4897-a433-50eacf8bc88d" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_dfa0d86a-ad63-4710-bd21-961b8aff33b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_3c7097c4-c303-46c3-b318-1ae56bfba4bc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_dfa0d86a-ad63-4710-bd21-961b8aff33b6" xlink:to="loc_us-gaap_CostOfSalesMember_3c7097c4-c303-46c3-b318-1ae56bfba4bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_c58a3e7d-188e-4730-8709-f14bd8cbda43" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SellingAndMarketingExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_dfa0d86a-ad63-4710-bd21-961b8aff33b6" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_c58a3e7d-188e-4730-8709-f14bd8cbda43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_fe23f0f5-89ce-4755-98d8-11c690246dc3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_dfa0d86a-ad63-4710-bd21-961b8aff33b6" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_fe23f0f5-89ce-4755-98d8-11c690246dc3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_7a7b30fc-488f-4055-88e1-56d7aaa16bd0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_dfa0d86a-ad63-4710-bd21-961b8aff33b6" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_7a7b30fc-488f-4055-88e1-56d7aaa16bd0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_f16d0006-cd7f-4e3b-93c8-492217571500" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5dae550f-ea2c-4f56-9f13-b77b8e682321" xlink:to="loc_us-gaap_AwardTypeAxis_f16d0006-cd7f-4e3b-93c8-492217571500" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f16d0006-cd7f-4e3b-93c8-492217571500_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_f16d0006-cd7f-4e3b-93c8-492217571500" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f16d0006-cd7f-4e3b-93c8-492217571500_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c4c45b91-86da-4ddb-9ba6-71e62380f51f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_f16d0006-cd7f-4e3b-93c8-492217571500" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c4c45b91-86da-4ddb-9ba6-71e62380f51f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_a11dfb0e-3728-4080-b873-3d68966a51a6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c4c45b91-86da-4ddb-9ba6-71e62380f51f" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_a11dfb0e-3728-4080-b873-3d68966a51a6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_1d37c847-0403-4f1f-8005-31a94a51c43b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c4c45b91-86da-4ddb-9ba6-71e62380f51f" xlink:to="loc_us-gaap_EmployeeStockOptionMember_1d37c847-0403-4f1f-8005-31a94a51c43b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_HoldCoUnitsMember_fe8c9762-8277-4ec8-96f6-bb0eb70bb158" xlink:href="zi-20201231.xsd#zi_HoldCoUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c4c45b91-86da-4ddb-9ba6-71e62380f51f" xlink:to="loc_zi_HoldCoUnitsMember_fe8c9762-8277-4ec8-96f6-bb0eb70bb158" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ClassPUnitsMember_577a3011-1d6c-466e-bea6-c4aae3610204" xlink:href="zi-20201231.xsd#zi_ClassPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c4c45b91-86da-4ddb-9ba6-71e62380f51f" xlink:to="loc_zi_ClassPUnitsMember_577a3011-1d6c-466e-bea6-c4aae3610204" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_LTIPUnitsMember_fe477a10-6e24-4d8b-a131-f56cf38fd2ff" xlink:href="zi-20201231.xsd#zi_LTIPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c4c45b91-86da-4ddb-9ba6-71e62380f51f" xlink:to="loc_zi_LTIPUnitsMember_fe477a10-6e24-4d8b-a131-f56cf38fd2ff" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_HSKBUnitsMember_8d50b6e5-c30f-4df7-9727-eb5d37fb31ea" xlink:href="zi-20201231.xsd#zi_HSKBUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c4c45b91-86da-4ddb-9ba6-71e62380f51f" xlink:to="loc_zi_HSKBUnitsMember_8d50b6e5-c30f-4df7-9727-eb5d37fb31ea" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PhantomUnitsMember_25004615-c6ee-4e1f-b0d4-ad98425b4d49" xlink:href="zi-20201231.xsd#zi_PhantomUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c4c45b91-86da-4ddb-9ba6-71e62380f51f" xlink:to="loc_zi_PhantomUnitsMember_25004615-c6ee-4e1f-b0d4-ad98425b4d49" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/SegmentandGeographicData" xlink:type="simple" xlink:href="zi-20201231.xsd#SegmentandGeographicData"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/SegmentandGeographicData" xlink:type="extended" id="i1a68d715557543c58c07e8da94299f93_SegmentandGeographicData"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/SegmentandGeographicDataTables" xlink:type="simple" xlink:href="zi-20201231.xsd#SegmentandGeographicDataTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/SegmentandGeographicDataTables" xlink:type="extended" id="i1691d930920e4feca025f809ef2fc94c_SegmentandGeographicDataTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/SegmentandGeographicDataDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#SegmentandGeographicDataDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/SegmentandGeographicDataDetails" xlink:type="extended" id="i0b497eda64464f12b72c99d0c2011d3b_SegmentandGeographicDataDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_815bfe4c-54c5-4d3f-893b-d97efed5002b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EntityWideRevenueMajorCustomerLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_60d6a236-77c2-414c-8754-f69cf74d4362" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_815bfe4c-54c5-4d3f-893b-d97efed5002b" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_60d6a236-77c2-414c-8754-f69cf74d4362" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_cea43ead-d3a4-4cee-b453-22d1b5b567d9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_815bfe4c-54c5-4d3f-893b-d97efed5002b" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_cea43ead-d3a4-4cee-b453-22d1b5b567d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_0b3783ef-1ac8-4e2a-a9fc-3a0499596d46" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_815bfe4c-54c5-4d3f-893b-d97efed5002b" xlink:to="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_0b3783ef-1ac8-4e2a-a9fc-3a0499596d46" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_06e56d00-68eb-4c62-90d0-b8ac9ebfab9c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_0b3783ef-1ac8-4e2a-a9fc-3a0499596d46" xlink:to="loc_srt_StatementGeographicalAxis_06e56d00-68eb-4c62-90d0-b8ac9ebfab9c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_06e56d00-68eb-4c62-90d0-b8ac9ebfab9c_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_06e56d00-68eb-4c62-90d0-b8ac9ebfab9c" xlink:to="loc_srt_SegmentGeographicalDomain_06e56d00-68eb-4c62-90d0-b8ac9ebfab9c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_35804bb0-055a-4166-8c53-4e339e22f833" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_06e56d00-68eb-4c62-90d0-b8ac9ebfab9c" xlink:to="loc_srt_SegmentGeographicalDomain_35804bb0-055a-4166-8c53-4e339e22f833" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_8ee9e2cf-2d9f-4cc1-9b6d-a847a8b0efe9" xlink:href="https://xbrl.sec.gov/country/2020/country-2020-01-31.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_35804bb0-055a-4166-8c53-4e339e22f833" xlink:to="loc_country_US_8ee9e2cf-2d9f-4cc1-9b6d-a847a8b0efe9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_5bc55b7e-5487-474d-a6cf-d164f8ea2f1a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_35804bb0-055a-4166-8c53-4e339e22f833" xlink:to="loc_us-gaap_NonUsMember_5bc55b7e-5487-474d-a6cf-d164f8ea2f1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_585685e8-84e2-4ded-b235-3ea23b1c4775" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_0b3783ef-1ac8-4e2a-a9fc-3a0499596d46" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_585685e8-84e2-4ded-b235-3ea23b1c4775" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_585685e8-84e2-4ded-b235-3ea23b1c4775_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_585685e8-84e2-4ded-b235-3ea23b1c4775" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_585685e8-84e2-4ded-b235-3ea23b1c4775_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_b67d4710-3712-4020-82ad-85ed31c8088e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_585685e8-84e2-4ded-b235-3ea23b1c4775" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_b67d4710-3712-4020-82ad-85ed31c8088e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicConcentrationRiskMember_48a33ce5-9fc5-4f4d-b268-0a816805ea57" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GeographicConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_b67d4710-3712-4020-82ad-85ed31c8088e" xlink:to="loc_us-gaap_GeographicConcentrationRiskMember_48a33ce5-9fc5-4f4d-b268-0a816805ea57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_54269159-7723-49a9-b1f6-ab3e81cfc94e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_0b3783ef-1ac8-4e2a-a9fc-3a0499596d46" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_54269159-7723-49a9-b1f6-ab3e81cfc94e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_54269159-7723-49a9-b1f6-ab3e81cfc94e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_54269159-7723-49a9-b1f6-ab3e81cfc94e" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_54269159-7723-49a9-b1f6-ab3e81cfc94e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_373979fd-b93d-4436-94c5-2e40243d7df3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_54269159-7723-49a9-b1f6-ab3e81cfc94e" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_373979fd-b93d-4436-94c5-2e40243d7df3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_699d454d-5019-4ea0-9bfd-d7ad87635c36" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_373979fd-b93d-4436-94c5-2e40243d7df3" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_699d454d-5019-4ea0-9bfd-d7ad87635c36" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/TaxReceivableAgreements" xlink:type="simple" xlink:href="zi-20201231.xsd#TaxReceivableAgreements"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/TaxReceivableAgreements" xlink:type="extended" id="ib154795697ef40c7a9b0d58bc5c9aede_TaxReceivableAgreements"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/TaxReceivableAgreementsDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#TaxReceivableAgreementsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/TaxReceivableAgreementsDetails" xlink:type="extended" id="i124a87fe7b394e478f10e0368e3acd75_TaxReceivableAgreementsDetails"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/IncomeTaxes" xlink:type="simple" xlink:href="zi-20201231.xsd#IncomeTaxes"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/IncomeTaxes" xlink:type="extended" id="if52925658fac421687341d037703c609_IncomeTaxes"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/IncomeTaxesTables" xlink:type="simple" xlink:href="zi-20201231.xsd#IncomeTaxesTables"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/IncomeTaxesTables" xlink:type="extended" id="ie3d880467eb14853ba32bb9423c328cb_IncomeTaxesTables"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/IncomeTaxesScheduleofIncomeTaxesDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#IncomeTaxesScheduleofIncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/IncomeTaxesScheduleofIncomeTaxesDetails" xlink:type="extended" id="i009119ea17984acba92d3593a49b20b5_IncomeTaxesScheduleofIncomeTaxesDetails"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/IncomeTaxesScheduleofEffectiveIncomeTaxReconciliationDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#IncomeTaxesScheduleofEffectiveIncomeTaxReconciliationDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/IncomeTaxesScheduleofEffectiveIncomeTaxReconciliationDetails" xlink:type="extended" id="ib092dd62c8f5476a8090c3597327fa13_IncomeTaxesScheduleofEffectiveIncomeTaxReconciliationDetails"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/IncomeTaxesDeferredTaxAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#IncomeTaxesDeferredTaxAssetsandLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/IncomeTaxesDeferredTaxAssetsandLiabilitiesDetails" xlink:type="extended" id="id2c5b810aa3a4cedb9e209db59ed6380_IncomeTaxesDeferredTaxAssetsandLiabilitiesDetails"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/IncomeTaxesNarrativeDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#IncomeTaxesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended" id="i11321976449f4a3199644bdea467df3a_IncomeTaxesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_29b619d0-b9c2-4e18-8ab4-7b1278281c01" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxContingencyLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_c8723f71-105d-408d-b1e3-a82fdbe46e9d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_29b619d0-b9c2-4e18-8ab4-7b1278281c01" xlink:to="loc_us-gaap_OperatingLossCarryforwards_c8723f71-105d-408d-b1e3-a82fdbe46e9d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardAmount_c8aac727-69c4-4a06-a6f9-055f2a8ff34c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TaxCreditCarryforwardAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_29b619d0-b9c2-4e18-8ab4-7b1278281c01" xlink:to="loc_us-gaap_TaxCreditCarryforwardAmount_c8aac727-69c4-4a06-a6f9-055f2a8ff34c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued_cc9376cc-0541-46c4-b472-2ebf40520bfb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_29b619d0-b9c2-4e18-8ab4-7b1278281c01" xlink:to="loc_us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued_cc9376cc-0541-46c4-b472-2ebf40520bfb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_a6b7220f-5d18-43e4-a8cf-8148104d2d8c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_29b619d0-b9c2-4e18-8ab4-7b1278281c01" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_a6b7220f-5d18-43e4-a8cf-8148104d2d8c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_943701d1-9ab5-4afa-b450-d966cc36a5e9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_29b619d0-b9c2-4e18-8ab4-7b1278281c01" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_943701d1-9ab5-4afa-b450-d966cc36a5e9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_b5058372-1804-49d1-a529-fd821b9cd4d2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxContingencyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_29b619d0-b9c2-4e18-8ab4-7b1278281c01" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_b5058372-1804-49d1-a529-fd821b9cd4d2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_c7b8671c-b119-4881-903c-31a56a624203" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_b5058372-1804-49d1-a529-fd821b9cd4d2" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_c7b8671c-b119-4881-903c-31a56a624203" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_c7b8671c-b119-4881-903c-31a56a624203_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_c7b8671c-b119-4881-903c-31a56a624203" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_c7b8671c-b119-4881-903c-31a56a624203_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_5c4cd032-a87b-46d6-b01b-40a49fa1f738" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_c7b8671c-b119-4881-903c-31a56a624203" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_5c4cd032-a87b-46d6-b01b-40a49fa1f738" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_aaff46e4-8741-4a21-9552-e1baa9f8ebb9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_5c4cd032-a87b-46d6-b01b-40a49fa1f738" xlink:to="loc_us-gaap_DomesticCountryMember_aaff46e4-8741-4a21-9552-e1baa9f8ebb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_bf2d53a4-5a2c-40d4-8a99-f7101321d6e4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_5c4cd032-a87b-46d6-b01b-40a49fa1f738" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_bf2d53a4-5a2c-40d4-8a99-f7101321d6e4" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/SubsequentEvents" xlink:type="simple" xlink:href="zi-20201231.xsd#SubsequentEvents"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/SubsequentEvents" xlink:type="extended" id="iab0676df3f054fc5b6c72c2646a515d6_SubsequentEvents"/>
  <link:roleRef roleURI="http://www.zoominfo.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="zi-20201231.xsd#SubsequentEventsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/SubsequentEventsDetails" xlink:type="extended" id="i267974c8cc82447bbd612755d461fea8_SubsequentEventsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_37472c12-9201-4cfa-a47e-f492edcbb678" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_daa55fe3-05e5-48e5-a9e8-2b06509bac2d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_37472c12-9201-4cfa-a47e-f492edcbb678" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_daa55fe3-05e5-48e5-a9e8-2b06509bac2d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_beb09441-e42e-4a8d-a37d-543043855e01" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_37472c12-9201-4cfa-a47e-f492edcbb678" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_beb09441-e42e-4a8d-a37d-543043855e01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExtinguishmentOfDebtAmount_095939e3-9250-4706-87fc-136fe7c75d0e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ExtinguishmentOfDebtAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_37472c12-9201-4cfa-a47e-f492edcbb678" xlink:to="loc_us-gaap_ExtinguishmentOfDebtAmount_095939e3-9250-4706-87fc-136fe7c75d0e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_cd5908f5-4f92-4781-9e45-9164fa01871c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_37472c12-9201-4cfa-a47e-f492edcbb678" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_cd5908f5-4f92-4781-9e45-9164fa01871c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_3781d775-4dff-4a95-bd76-e12a00da40cc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_37472c12-9201-4cfa-a47e-f492edcbb678" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_3781d775-4dff-4a95-bd76-e12a00da40cc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_NonCancelableLeaseAgreementTerm_c64800eb-0e83-4467-96df-3d23a796478a" xlink:href="zi-20201231.xsd#zi_NonCancelableLeaseAgreementTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_37472c12-9201-4cfa-a47e-f492edcbb678" xlink:to="loc_zi_NonCancelableLeaseAgreementTerm_c64800eb-0e83-4467-96df-3d23a796478a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_NetRentedArea_0a170de1-e5f1-4b1c-9ce7-470931dda910" xlink:href="zi-20201231.xsd#zi_NetRentedArea"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_37472c12-9201-4cfa-a47e-f492edcbb678" xlink:to="loc_zi_NetRentedArea_0a170de1-e5f1-4b1c-9ce7-470931dda910" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_NetRentedAreaWithPlansToExtend_5a2ba474-1c71-4f06-b784-1c606b26ed4a" xlink:href="zi-20201231.xsd#zi_NetRentedAreaWithPlansToExtend"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_37472c12-9201-4cfa-a47e-f492edcbb678" xlink:to="loc_zi_NetRentedAreaWithPlansToExtend_5a2ba474-1c71-4f06-b784-1c606b26ed4a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PaymentsForRentPerSquareFoot_96e2b6a7-a517-467b-966b-de37f2c81c73" xlink:href="zi-20201231.xsd#zi_PaymentsForRentPerSquareFoot"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_37472c12-9201-4cfa-a47e-f492edcbb678" xlink:to="loc_zi_PaymentsForRentPerSquareFoot_96e2b6a7-a517-467b-966b-de37f2c81c73" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_acc32bc9-aef4-4400-96a6-4fe189f69b04" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_37472c12-9201-4cfa-a47e-f492edcbb678" xlink:to="loc_us-gaap_SubsequentEventTable_acc32bc9-aef4-4400-96a6-4fe189f69b04" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_98242a94-31c6-4b98-a0a0-d0870e279860" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_acc32bc9-aef4-4400-96a6-4fe189f69b04" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_98242a94-31c6-4b98-a0a0-d0870e279860" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_98242a94-31c6-4b98-a0a0-d0870e279860_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_98242a94-31c6-4b98-a0a0-d0870e279860" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_98242a94-31c6-4b98-a0a0-d0870e279860_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_3f9fc695-0e12-40fe-85e5-b6cdb9578a5b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_98242a94-31c6-4b98-a0a0-d0870e279860" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_3f9fc695-0e12-40fe-85e5-b6cdb9578a5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_eca1ad23-d964-4bf6-aadf-b3d080a03024" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_3f9fc695-0e12-40fe-85e5-b6cdb9578a5b" xlink:to="loc_us-gaap_SubsequentEventMember_eca1ad23-d964-4bf6-aadf-b3d080a03024" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_84e236e6-c5e9-4ff9-8baf-bedd66c2150a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_acc32bc9-aef4-4400-96a6-4fe189f69b04" xlink:to="loc_us-gaap_DebtInstrumentAxis_84e236e6-c5e9-4ff9-8baf-bedd66c2150a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_84e236e6-c5e9-4ff9-8baf-bedd66c2150a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_84e236e6-c5e9-4ff9-8baf-bedd66c2150a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_84e236e6-c5e9-4ff9-8baf-bedd66c2150a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_be4b9494-f31f-46ed-9e8a-aa5f9f64fe96" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_84e236e6-c5e9-4ff9-8baf-bedd66c2150a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_be4b9494-f31f-46ed-9e8a-aa5f9f64fe96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_FirstLienTermLoanMember_1d846a5d-f39f-43ef-872a-dfea0a6677cd" xlink:href="zi-20201231.xsd#zi_FirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_be4b9494-f31f-46ed-9e8a-aa5f9f64fe96" xlink:to="loc_zi_FirstLienTermLoanMember_1d846a5d-f39f-43ef-872a-dfea0a6677cd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_94b43161-f546-4bee-8d0b-6c2e745f05ff" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_acc32bc9-aef4-4400-96a6-4fe189f69b04" xlink:to="loc_srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_94b43161-f546-4bee-8d0b-6c2e745f05ff" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_94b43161-f546-4bee-8d0b-6c2e745f05ff_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MortgageLoansOnRealEstateNamePropertyTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_94b43161-f546-4bee-8d0b-6c2e745f05ff" xlink:to="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_94b43161-f546-4bee-8d0b-6c2e745f05ff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_217de745-8372-4ddd-8b9c-d847002cf126" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MortgageLoansOnRealEstateNamePropertyTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_94b43161-f546-4bee-8d0b-6c2e745f05ff" xlink:to="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_217de745-8372-4ddd-8b9c-d847002cf126" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OfficeBuildingMember_2ad3c232-d360-4099-95fd-c30bc64d3a4b" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OfficeBuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_217de745-8372-4ddd-8b9c-d847002cf126" xlink:to="loc_srt_OfficeBuildingMember_2ad3c232-d360-4099-95fd-c30bc64d3a4b" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
