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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019fed21-30e2-712e-98a8-db82aeeb9ad1,g:e57d9053-d91b-4421-ae22-6b1a08b5b0fc-->
<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/ConsolidatedStatementsofOperationsParenthetical" xlink:type="simple" xlink:href="zi-20260930.xsd#ConsolidatedStatementsofOperationsParenthetical"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/ConsolidatedStatementsofOperationsParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fed21-323e-7fc4-a125-8c8d6e945740" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019fed21-323e-7899-903b-094516a16f67" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019fed21-323e-7fc4-a125-8c8d6e945740" xlink:to="loc_us-gaap_StatementTable_019fed21-323e-7899-903b-094516a16f67" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019fed21-323e-786c-a1ec-8b3cb14f7ebf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019fed21-323e-7899-903b-094516a16f67" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019fed21-323e-786c-a1ec-8b3cb14f7ebf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019fed21-323e-7f3b-bd79-1330e6698e3f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fed21-323e-7fc4-a125-8c8d6e945740" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019fed21-323e-7f3b-bd79-1330e6698e3f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/ConsolidatedStatementsofOperationsParenthetical_1" xlink:type="simple" xlink:href="zi-20260930.xsd#ConsolidatedStatementsofOperationsParenthetical_1"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/ConsolidatedStatementsofOperationsParenthetical_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fed21-323e-7fc4-a125-8c8d6e945740" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019fed21-323e-7899-903b-094516a16f67" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019fed21-323e-7fc4-a125-8c8d6e945740" xlink:to="loc_us-gaap_StatementTable_019fed21-323e-7899-903b-094516a16f67" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019fed21-323e-7f3b-bd79-1330e6698e3f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fed21-323e-7fc4-a125-8c8d6e945740" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019fed21-323e-7f3b-bd79-1330e6698e3f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/ConsolidatedStatementsofChangesinStockholdersEquity" xlink:type="simple" xlink:href="zi-20260930.xsd#ConsolidatedStatementsofChangesinStockholdersEquity"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/ConsolidatedStatementsofChangesinStockholdersEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fed21-323e-7772-85be-c33aa3905b11" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019fed21-323e-7023-984c-1319e7cac60d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019fed21-323e-7772-85be-c33aa3905b11" xlink:to="loc_us-gaap_StatementTable_019fed21-323e-7023-984c-1319e7cac60d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019fed21-323e-78ff-a7e8-eb8f59856fb1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019fed21-323e-7023-984c-1319e7cac60d" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019fed21-323e-78ff-a7e8-eb8f59856fb1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019fed21-323e-78ff-a7e8-eb8f59856fb1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019fed21-323e-78ff-a7e8-eb8f59856fb1" xlink:to="loc_us-gaap_EquityComponentDomain_019fed21-323e-78ff-a7e8-eb8f59856fb1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019fed21-323e-7f6c-812b-ff5f7525205b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019fed21-323e-78ff-a7e8-eb8f59856fb1" xlink:to="loc_us-gaap_EquityComponentDomain_019fed21-323e-7f6c-812b-ff5f7525205b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019fed21-323e-72ec-8554-d4df347ea49f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fed21-323e-7f6c-812b-ff5f7525205b" xlink:to="loc_us-gaap_CommonStockMember_019fed21-323e-72ec-8554-d4df347ea49f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019fed21-323e-7c47-a461-1ce93e753379" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fed21-323e-7f6c-812b-ff5f7525205b" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019fed21-323e-7c47-a461-1ce93e753379" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019fed21-323e-7e89-b15d-583f2fba1690" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fed21-323e-7f6c-812b-ff5f7525205b" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019fed21-323e-7e89-b15d-583f2fba1690" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019fed21-323e-734a-b21f-fef6ad3219cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fed21-323e-7f6c-812b-ff5f7525205b" xlink:to="loc_us-gaap_RetainedEarningsMember_019fed21-323e-734a-b21f-fef6ad3219cb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fed21-323e-7740-bd4a-edb361e88bc9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fed21-323e-7772-85be-c33aa3905b11" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fed21-323e-7740-bd4a-edb361e88bc9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019fed21-323e-7bbe-b34f-1820fc9ba606" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fed21-323e-7740-bd4a-edb361e88bc9" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019fed21-323e-7bbe-b34f-1820fc9ba606" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019fed21-323e-7b93-a8e0-5ab8776a3823" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fed21-323e-7740-bd4a-edb361e88bc9" xlink:to="loc_us-gaap_StockholdersEquity_019fed21-323e-7b93-a8e0-5ab8776a3823" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019fed21-323e-766a-b49a-afa39a26195d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fed21-323e-7740-bd4a-edb361e88bc9" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019fed21-323e-766a-b49a-afa39a26195d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_019fed21-323e-75c6-938e-fdcb924aaffc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fed21-323e-7740-bd4a-edb361e88bc9" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_019fed21-323e-75c6-938e-fdcb924aaffc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019fed21-323e-70f5-ab08-9278bea8adc4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fed21-323e-7740-bd4a-edb361e88bc9" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019fed21-323e-70f5-ab08-9278bea8adc4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_019fed21-323e-7480-b481-58a6dfb011b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fed21-323e-7740-bd4a-edb361e88bc9" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_019fed21-323e-7480-b481-58a6dfb011b3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_019fed21-323e-7006-86d7-c64bbce86f39" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fed21-323e-7740-bd4a-edb361e88bc9" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_019fed21-323e-7006-86d7-c64bbce86f39" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019fed21-323e-76ca-a9d3-4a7cd8c9ffbd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fed21-323e-7740-bd4a-edb361e88bc9" xlink:to="loc_us-gaap_NetIncomeLoss_019fed21-323e-76ca-a9d3-4a7cd8c9ffbd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019fed21-323e-7b84-92da-d2a57b709f6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fed21-323e-7740-bd4a-edb361e88bc9" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019fed21-323e-7b84-92da-d2a57b709f6e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019fed21-323e-7076-ab04-62817505af3f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fed21-323e-7740-bd4a-edb361e88bc9" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019fed21-323e-7076-ab04-62817505af3f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019fed21-323e-71e8-a5d7-780debd50b81" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019fed21-323e-7398-859d-716531054756" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/BusinessBasisofPresentationandSummaryofSignificantAccountingPoliciesDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#BusinessBasisofPresentationandSummaryofSignificantAccountingPoliciesDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/BusinessBasisofPresentationandSummaryofSignificantAccountingPoliciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-323e-742b-822b-7aaa9da634a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-323e-742b-822b-7aaa9da634a6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019fed21-323e-76d4-9c0d-73b49a561f83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfFinancialPositionLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-323e-742b-822b-7aaa9da634a6" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019fed21-323e-76d4-9c0d-73b49a561f83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseCurrent_019fed21-323e-7cdf-82b6-8c86b7f5bca7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_PrepaidExpenseCurrent_019fed21-323e-7cdf-82b6-8c86b7f5bca7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedSalesCommissionCurrentAndNoncurrent_019fed21-323e-7d63-87bc-67203e01cea7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedSalesCommissionCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_AccruedSalesCommissionCurrentAndNoncurrent_019fed21-323e-7d63-87bc-67203e01cea7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedSalesCommissionCurrent_019fed21-323e-735e-a288-70ad72ece71f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedSalesCommissionCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_AccruedSalesCommissionCurrent_019fed21-323e-735e-a288-70ad72ece71f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_AccruedSalesCommissionNoncurrent_019fed21-323e-7396-bb61-64789bf3c4da" xlink:href="zi-20260930.xsd#zi_AccruedSalesCommissionNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_zi_AccruedSalesCommissionNoncurrent_019fed21-323e-7396-bb61-64789bf3c4da" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019fed21-323e-7e22-95c9-051edd54c89d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019fed21-323e-7e22-95c9-051edd54c89d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_019fed21-323e-7d19-b638-28c143df5221" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_019fed21-323e-7d19-b638-28c143df5221" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019fed21-323e-70f1-b581-b7ef1a11d2f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019fed21-323e-70f1-b581-b7ef1a11d2f8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_019fed21-323e-7891-ad1d-c1a431182a9c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_019fed21-323e-7891-ad1d-c1a431182a9c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019fed21-323e-7182-acbd-376b5ec51d9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019fed21-323e-7182-acbd-376b5ec51d9b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramExciseTax_019fed21-323e-7992-87d3-a34a0c478fef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareRepurchaseProgramExciseTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_ShareRepurchaseProgramExciseTax_019fed21-323e-7992-87d3-a34a0c478fef" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_019fed21-323e-71a3-9f79-38c4b155d41f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_019fed21-323e-71a3-9f79-38c4b155d41f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent_019fed21-323e-7a7b-bef0-3bdca3a580bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent_019fed21-323e-7a7b-bef0-3bdca3a580bb" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostIncurredCost_019fed21-323e-7611-ba3a-a8293f461427" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostIncurredCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_RestructuringAndRelatedCostIncurredCost_019fed21-323e-7611-ba3a-a8293f461427" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRestructuring_019fed21-323e-765b-9f23-45b900bd1b51" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRestructuring"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_PaymentsForRestructuring_019fed21-323e-765b-9f23-45b900bd1b51" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1_019fed21-323e-7d39-9daa-b0852ba18b60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1_019fed21-323e-7d39-9daa-b0852ba18b60" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostExpectedCost1_01a17b42-6eb8-71a0-8294-ba7f34ac78d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostExpectedCost1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_RestructuringAndRelatedCostExpectedCost1_01a17b42-6eb8-71a0-8294-ba7f34ac78d4" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/BusinessBasisofPresentationandSummaryofSignificantAccountingPoliciesDetails_1" xlink:type="simple" xlink:href="zi-20260930.xsd#BusinessBasisofPresentationandSummaryofSignificantAccountingPoliciesDetails_1"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/BusinessBasisofPresentationandSummaryofSignificantAccountingPoliciesDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-323e-742b-822b-7aaa9da634a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-323e-742b-822b-7aaa9da634a6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseCurrent_019fed21-323e-7cdf-82b6-8c86b7f5bca7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_PrepaidExpenseCurrent_019fed21-323e-7cdf-82b6-8c86b7f5bca7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedSalesCommissionCurrentAndNoncurrent_019fed21-323e-7d63-87bc-67203e01cea7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedSalesCommissionCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_AccruedSalesCommissionCurrentAndNoncurrent_019fed21-323e-7d63-87bc-67203e01cea7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedSalesCommissionCurrent_019fed21-323e-735e-a288-70ad72ece71f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedSalesCommissionCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_AccruedSalesCommissionCurrent_019fed21-323e-735e-a288-70ad72ece71f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_AccruedSalesCommissionNoncurrent_019fed21-323e-7396-bb61-64789bf3c4da" xlink:href="zi-20260930.xsd#zi_AccruedSalesCommissionNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_zi_AccruedSalesCommissionNoncurrent_019fed21-323e-7396-bb61-64789bf3c4da" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019fed21-323e-7e22-95c9-051edd54c89d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019fed21-323e-7e22-95c9-051edd54c89d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_019fed21-323e-7d19-b638-28c143df5221" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_019fed21-323e-7d19-b638-28c143df5221" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019fed21-323e-70f1-b581-b7ef1a11d2f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019fed21-323e-70f1-b581-b7ef1a11d2f8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_019fed21-323e-7891-ad1d-c1a431182a9c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_019fed21-323e-7891-ad1d-c1a431182a9c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019fed21-323e-7182-acbd-376b5ec51d9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019fed21-323e-7182-acbd-376b5ec51d9b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramExciseTax_019fed21-323e-7992-87d3-a34a0c478fef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareRepurchaseProgramExciseTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_ShareRepurchaseProgramExciseTax_019fed21-323e-7992-87d3-a34a0c478fef" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_019fed21-323e-71a3-9f79-38c4b155d41f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_019fed21-323e-71a3-9f79-38c4b155d41f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent_019fed21-323e-7a7b-bef0-3bdca3a580bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent_019fed21-323e-7a7b-bef0-3bdca3a580bb" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostIncurredCost_019fed21-323e-7611-ba3a-a8293f461427" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostIncurredCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_RestructuringAndRelatedCostIncurredCost_019fed21-323e-7611-ba3a-a8293f461427" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRestructuring_019fed21-323e-765b-9f23-45b900bd1b51" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRestructuring"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_PaymentsForRestructuring_019fed21-323e-765b-9f23-45b900bd1b51" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1_019fed21-323e-7d39-9daa-b0852ba18b60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1_019fed21-323e-7d39-9daa-b0852ba18b60" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostExpectedCost1_01a17b42-6eb8-71a0-8294-ba7f34ac78d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostExpectedCost1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-323e-7eba-a30e-f9d4c5b5a4ef" xlink:to="loc_us-gaap_RestructuringAndRelatedCostExpectedCost1_01a17b42-6eb8-71a0-8294-ba7f34ac78d4" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/RevenuefromContractswithCustomersRevenueDisaggregatedbyServiceOfferingDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#RevenuefromContractswithCustomersRevenueDisaggregatedbyServiceOfferingDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/RevenuefromContractswithCustomersRevenueDisaggregatedbyServiceOfferingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019fed21-323e-7f26-88cd-d1d6d96c8774" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019fed21-323e-7256-ae8d-fdbe492b7166" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019fed21-323e-7f26-88cd-d1d6d96c8774" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019fed21-323e-7256-ae8d-fdbe492b7166" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019fed21-323e-7943-b14e-208c549c4c34" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019fed21-323e-7256-ae8d-fdbe492b7166" xlink:to="loc_srt_ProductOrServiceAxis_019fed21-323e-7943-b14e-208c549c4c34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fed21-323e-7943-b14e-208c549c4c34_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019fed21-323e-7943-b14e-208c549c4c34" xlink:to="loc_srt_ProductsAndServicesDomain_019fed21-323e-7943-b14e-208c549c4c34_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fed21-323e-7416-b3b7-cd0f7f4e67f5" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019fed21-323e-7943-b14e-208c549c4c34" xlink:to="loc_srt_ProductsAndServicesDomain_019fed21-323e-7416-b3b7-cd0f7f4e67f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubscriptionAndCirculationMember_019fed21-323e-7ba3-90ff-051a628cf410" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubscriptionAndCirculationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fed21-323e-7416-b3b7-cd0f7f4e67f5" xlink:to="loc_us-gaap_SubscriptionAndCirculationMember_019fed21-323e-7ba3-90ff-051a628cf410" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_EmailVerificationServiceAndContactDataMember_019fed21-323e-764c-b84e-0ddca57e49bf" xlink:href="zi-20260930.xsd#zi_EmailVerificationServiceAndContactDataMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fed21-323e-7416-b3b7-cd0f7f4e67f5" xlink:to="loc_zi_EmailVerificationServiceAndContactDataMember_019fed21-323e-764c-b84e-0ddca57e49bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_OtherServiceMember_019fed21-323e-73d1-a66e-737e71ca4357" xlink:href="zi-20260930.xsd#zi_OtherServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fed21-323e-7416-b3b7-cd0f7f4e67f5" xlink:to="loc_zi_OtherServiceMember_019fed21-323e-73d1-a66e-737e71ca4357" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fed21-323e-76be-a1c2-bd49407a52af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019fed21-323e-7f26-88cd-d1d6d96c8774" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fed21-323e-76be-a1c2-bd49407a52af" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019fed21-323e-707a-b9f0-3aff059810d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019fed21-323e-74f5-bbb8-8be13d74e31d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019fed21-323e-707a-b9f0-3aff059810d6" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019fed21-323e-74f5-bbb8-8be13d74e31d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_019fed21-323e-7594-9493-79fd263b6445" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019fed21-323e-74f5-bbb8-8be13d74e31d" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_019fed21-323e-7594-9493-79fd263b6445" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019fed21-323e-7a40-8fa9-b7b45335a20b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019fed21-323e-74f5-bbb8-8be13d74e31d" xlink:to="loc_srt_RangeAxis_019fed21-323e-7a40-8fa9-b7b45335a20b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fed21-323e-7a40-8fa9-b7b45335a20b_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019fed21-323e-7a40-8fa9-b7b45335a20b" xlink:to="loc_srt_RangeMember_019fed21-323e-7a40-8fa9-b7b45335a20b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fed21-323e-7823-a687-921f423ca317" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019fed21-323e-7a40-8fa9-b7b45335a20b" xlink:to="loc_srt_RangeMember_019fed21-323e-7823-a687-921f423ca317" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019fed21-323e-7380-b036-84731ac86907" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fed21-323e-7823-a687-921f423ca317" xlink:to="loc_srt_MinimumMember_019fed21-323e-7380-b036-84731ac86907" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019fed21-323e-74fa-a340-a03caba5a238" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fed21-323e-7823-a687-921f423ca317" xlink:to="loc_srt_MaximumMember_019fed21-323e-74fa-a340-a03caba5a238" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019fed21-323e-735f-af8a-466b14045af8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019fed21-323e-707a-b9f0-3aff059810d6" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019fed21-323e-735f-af8a-466b14045af8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_019fed21-323e-7058-90d2-03cbc186d905" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019fed21-323e-707a-b9f0-3aff059810d6" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_019fed21-323e-7058-90d2-03cbc186d905" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails_1" xlink:type="simple" xlink:href="zi-20260930.xsd#RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails_1"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/RevenuefromContractswithCustomersRemainingPerformanceObligationsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019fed21-323e-707a-b9f0-3aff059810d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019fed21-323e-74f5-bbb8-8be13d74e31d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019fed21-323e-707a-b9f0-3aff059810d6" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019fed21-323e-74f5-bbb8-8be13d74e31d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019fed21-323e-7a40-8fa9-b7b45335a20b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019fed21-323e-74f5-bbb8-8be13d74e31d" xlink:to="loc_srt_RangeAxis_019fed21-323e-7a40-8fa9-b7b45335a20b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fed21-323e-7a40-8fa9-b7b45335a20b_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019fed21-323e-7a40-8fa9-b7b45335a20b" xlink:to="loc_srt_RangeMember_019fed21-323e-7a40-8fa9-b7b45335a20b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fed21-323e-7823-a687-921f423ca317" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019fed21-323e-7a40-8fa9-b7b45335a20b" xlink:to="loc_srt_RangeMember_019fed21-323e-7823-a687-921f423ca317" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019fed21-323e-7380-b036-84731ac86907" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fed21-323e-7823-a687-921f423ca317" xlink:to="loc_srt_MinimumMember_019fed21-323e-7380-b036-84731ac86907" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019fed21-323e-74fa-a340-a03caba5a238" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fed21-323e-7823-a687-921f423ca317" xlink:to="loc_srt_MaximumMember_019fed21-323e-74fa-a340-a03caba5a238" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019fed21-323e-735f-af8a-466b14045af8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019fed21-323e-707a-b9f0-3aff059810d6" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019fed21-323e-735f-af8a-466b14045af8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_019fed21-323e-7058-90d2-03cbc186d905" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019fed21-323e-707a-b9f0-3aff059810d6" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_019fed21-323e-7058-90d2-03cbc186d905" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/InvestmentsComponentsDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#InvestmentsComponentsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/InvestmentsComponentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fed21-323e-7485-9ded-43358911eb16" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019fed21-323e-7801-9854-04596ccce04f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fed21-323e-7485-9ded-43358911eb16" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019fed21-323e-7801-9854-04596ccce04f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019fed21-323e-70bb-8a17-916255d69e05" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019fed21-323e-7801-9854-04596ccce04f" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019fed21-323e-70bb-8a17-916255d69e05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-323e-70bb-8a17-916255d69e05_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fed21-323e-70bb-8a17-916255d69e05" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-323e-70bb-8a17-916255d69e05_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-323e-7117-88a9-5d2d31920cca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fed21-323e-70bb-8a17-916255d69e05" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-323e-7117-88a9-5d2d31920cca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_019fed21-323e-7520-93d9-2c307b537c88" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-323e-7117-88a9-5d2d31920cca" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_019fed21-323e-7520-93d9-2c307b537c88" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_019fed21-323e-7e6f-9d03-d746b0210958" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-323e-7117-88a9-5d2d31920cca" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_019fed21-323e-7e6f-9d03-d746b0210958" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019fed21-323e-7bf4-9dc1-8e648bc092ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fed21-323e-7485-9ded-43358911eb16" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019fed21-323e-7bf4-9dc1-8e648bc092ad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019fed21-323e-7069-a16c-78b02f49e3ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fed21-323e-7485-9ded-43358911eb16" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019fed21-323e-7069-a16c-78b02f49e3ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019fed21-323e-7fba-b93b-ec7a46c1a168" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fed21-323e-7485-9ded-43358911eb16" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019fed21-323e-7fba-b93b-ec7a46c1a168" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019fed21-323e-7344-96fb-abd68fbb98c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019fed21-323e-7485-9ded-43358911eb16" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019fed21-323e-7344-96fb-abd68fbb98c1" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/GoodwillandAcquiredIntangibleAssetsIntangibleAssetsDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#GoodwillandAcquiredIntangibleAssetsIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/GoodwillandAcquiredIntangibleAssetsIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019fed21-323f-764a-bb76-a047b2adfb08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_019fed21-323f-70e6-81c4-d48060fb64ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019fed21-323f-764a-bb76-a047b2adfb08" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_019fed21-323f-70e6-81c4-d48060fb64ef" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019fed21-323f-72ba-a9dc-72557f084437" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_019fed21-323f-70e6-81c4-d48060fb64ef" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019fed21-323f-72ba-a9dc-72557f084437" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fed21-323f-72ba-a9dc-72557f084437_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019fed21-323f-72ba-a9dc-72557f084437" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fed21-323f-72ba-a9dc-72557f084437_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fed21-323f-7609-be74-9a3082855602" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019fed21-323f-72ba-a9dc-72557f084437" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fed21-323f-7609-be74-9a3082855602" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019fed21-323f-71e0-895a-478bfa1a820d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fed21-323f-7609-be74-9a3082855602" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019fed21-323f-71e0-895a-478bfa1a820d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_019fed21-323f-72e2-afe6-06b9112e262f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fed21-323f-7609-be74-9a3082855602" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_019fed21-323f-72e2-afe6-06b9112e262f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_BrandPortfolioMember_019fed21-323f-7f48-a33d-f8c9bd8c62bd" xlink:href="zi-20260930.xsd#zi_BrandPortfolioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019fed21-323f-7609-be74-9a3082855602" xlink:to="loc_zi_BrandPortfolioMember_019fed21-323f-7f48-a33d-f8c9bd8c62bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019fed21-323f-7002-9421-14d035b04714" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019fed21-323f-764a-bb76-a047b2adfb08" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019fed21-323f-7002-9421-14d035b04714" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019fed21-323f-7c56-8cf9-ed63ccff46c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019fed21-323f-764a-bb76-a047b2adfb08" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019fed21-323f-7c56-8cf9-ed63ccff46c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019fed21-323f-7cec-ab30-2ff87257f539" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_019fed21-323f-764a-bb76-a047b2adfb08" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019fed21-323f-7cec-ab30-2ff87257f539" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019fed21-323f-7dee-86e3-1bc1499268dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_019fed21-323f-7db1-a214-27d9d71d42b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019fed21-323f-7dee-86e3-1bc1499268dd" xlink:to="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_019fed21-323f-7db1-a214-27d9d71d42b2" xlink:type="arc" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019fed21-323f-7525-861b-5c4d2df75249" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_019fed21-323f-7db1-a214-27d9d71d42b2" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019fed21-323f-7525-861b-5c4d2df75249" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019fed21-323f-7525-861b-5c4d2df75249_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019fed21-323f-7525-861b-5c4d2df75249" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019fed21-323f-7525-861b-5c4d2df75249_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019fed21-323f-701f-afc2-183ba17ea8af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019fed21-323f-7525-861b-5c4d2df75249" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019fed21-323f-701f-afc2-183ba17ea8af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PreAcquisitionBrandPortfolioMember_019fed21-323f-7854-9a8f-0d55a3370295" xlink:href="zi-20260930.xsd#zi_PreAcquisitionBrandPortfolioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019fed21-323f-701f-afc2-183ba17ea8af" xlink:to="loc_zi_PreAcquisitionBrandPortfolioMember_019fed21-323f-7854-9a8f-0d55a3370295" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_019fed21-323f-74e5-ab93-3394fd7d9437" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019fed21-323f-7dee-86e3-1bc1499268dd" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_019fed21-323f-74e5-ab93-3394fd7d9437" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_019fed21-323f-7541-9194-9355e31bcdce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019fed21-323f-7dee-86e3-1bc1499268dd" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_019fed21-323f-7541-9194-9355e31bcdce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019fed21-323f-71bd-93cd-85e10fd6a419" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019fed21-323f-7dee-86e3-1bc1499268dd" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019fed21-323f-71bd-93cd-85e10fd6a419" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/FinancingArrangementsCarryingValuesofBorrowingsDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#FinancingArrangementsCarryingValuesofBorrowingsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/FinancingArrangementsCarryingValuesofBorrowingsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-781c-bf51-6baece770808" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019fed21-323f-70e4-8cb5-c5aefe915507" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-781c-bf51-6baece770808" xlink:to="loc_us-gaap_DebtInstrumentTable_019fed21-323f-70e4-8cb5-c5aefe915507" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019fed21-323f-7209-9449-cf622b257c6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fed21-323f-70e4-8cb5-c5aefe915507" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019fed21-323f-7209-9449-cf622b257c6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fed21-323f-7209-9449-cf622b257c6c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019fed21-323f-7209-9449-cf622b257c6c" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fed21-323f-7209-9449-cf622b257c6c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fed21-323f-7c23-9f6f-8c73f3cd9aad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019fed21-323f-7209-9449-cf622b257c6c" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fed21-323f-7c23-9f6f-8c73f3cd9aad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019fed21-323f-7d6c-b7e7-80b2e5b5f929" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fed21-323f-7c23-9f6f-8c73f3cd9aad" xlink:to="loc_us-gaap_SecuredDebtMember_019fed21-323f-7d6c-b7e7-80b2e5b5f929" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019fed21-323f-78bc-9326-70d0a8c02c12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fed21-323f-7c23-9f6f-8c73f3cd9aad" xlink:to="loc_us-gaap_SeniorNotesMember_019fed21-323f-78bc-9326-70d0a8c02c12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019fed21-323f-7f9b-b1c9-ff96878bebce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fed21-323f-70e4-8cb5-c5aefe915507" xlink:to="loc_us-gaap_DebtInstrumentAxis_019fed21-323f-7f9b-b1c9-ff96878bebce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fed21-323f-7f9b-b1c9-ff96878bebce_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fed21-323f-7f9b-b1c9-ff96878bebce" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fed21-323f-7f9b-b1c9-ff96878bebce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fed21-323f-7596-9f10-8058bda211a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fed21-323f-7f9b-b1c9-ff96878bebce" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fed21-323f-7596-9f10-8058bda211a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_FirstLienTermLoanMember_019fed21-323f-7c3a-a4ef-aa6e3aeedc8c" xlink:href="zi-20260930.xsd#zi_FirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fed21-323f-7596-9f10-8058bda211a8" xlink:to="loc_zi_FirstLienTermLoanMember_019fed21-323f-7c3a-a4ef-aa6e3aeedc8c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_A3875SeniorNotesMember_019fed21-323f-780b-a346-fddbdd31bfdd" xlink:href="zi-20260930.xsd#zi_A3875SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fed21-323f-7596-9f10-8058bda211a8" xlink:to="loc_zi_A3875SeniorNotesMember_019fed21-323f-780b-a346-fddbdd31bfdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019fed21-323f-7398-bf9a-64f1606e5df3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fed21-323f-70e4-8cb5-c5aefe915507" xlink:to="loc_us-gaap_CreditFacilityAxis_019fed21-323f-7398-bf9a-64f1606e5df3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019fed21-323f-7398-bf9a-64f1606e5df3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019fed21-323f-7398-bf9a-64f1606e5df3" xlink:to="loc_us-gaap_CreditFacilityDomain_019fed21-323f-7398-bf9a-64f1606e5df3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019fed21-323f-7888-bb28-5ec8ac81c133" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019fed21-323f-7398-bf9a-64f1606e5df3" xlink:to="loc_us-gaap_CreditFacilityDomain_019fed21-323f-7888-bb28-5ec8ac81c133" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019fed21-323f-7210-8961-5483a6d0a65e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019fed21-323f-7888-bb28-5ec8ac81c133" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019fed21-323f-7210-8961-5483a6d0a65e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019fed21-323f-7281-942f-783a12977bcf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-781c-bf51-6baece770808" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019fed21-323f-7281-942f-783a12977bcf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019fed21-323f-75bb-9432-22c4681a621f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-781c-bf51-6baece770808" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019fed21-323f-75bb-9432-22c4681a621f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019fed21-323f-7026-8fcd-2834e6e542e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-781c-bf51-6baece770808" xlink:to="loc_us-gaap_LongTermDebt_019fed21-323f-7026-8fcd-2834e6e542e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019fed21-323f-7a62-928a-719bb8ab8225" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-781c-bf51-6baece770808" xlink:to="loc_us-gaap_LineOfCredit_019fed21-323f-7a62-928a-719bb8ab8225" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019fed21-323f-7aea-9821-822ba7159785" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-781c-bf51-6baece770808" xlink:to="loc_us-gaap_LongTermDebtCurrent_019fed21-323f-7aea-9821-822ba7159785" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019fed21-323f-768f-abcf-72d5b1abfd36" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-781c-bf51-6baece770808" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019fed21-323f-768f-abcf-72d5b1abfd36" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/FinancingArrangementsNarrativeDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#FinancingArrangementsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/FinancingArrangementsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-77d2-8653-e9a209bfd927" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019fed21-323f-7977-b8ed-1c7c6c41f7c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-77d2-8653-e9a209bfd927" xlink:to="loc_us-gaap_DebtInstrumentTable_019fed21-323f-7977-b8ed-1c7c6c41f7c2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019fed21-323f-7f47-b266-9e2e6f1d8df7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fed21-323f-7977-b8ed-1c7c6c41f7c2" xlink:to="loc_us-gaap_DebtInstrumentAxis_019fed21-323f-7f47-b266-9e2e6f1d8df7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fed21-323f-7f47-b266-9e2e6f1d8df7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fed21-323f-7f47-b266-9e2e6f1d8df7" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fed21-323f-7f47-b266-9e2e6f1d8df7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fed21-323f-7fa6-a47e-cf4c3cda0ff7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fed21-323f-7f47-b266-9e2e6f1d8df7" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fed21-323f-7fa6-a47e-cf4c3cda0ff7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_FirstLienTermLoanMember_019fed21-323f-7e03-804d-666655497544" xlink:href="zi-20260930.xsd#zi_FirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fed21-323f-7fa6-a47e-cf4c3cda0ff7" xlink:to="loc_zi_FirstLienTermLoanMember_019fed21-323f-7e03-804d-666655497544" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_A3875SeniorNotesMember_019fed21-323f-752c-b195-e64b08589c67" xlink:href="zi-20260930.xsd#zi_A3875SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fed21-323f-7fa6-a47e-cf4c3cda0ff7" xlink:to="loc_zi_A3875SeniorNotesMember_019fed21-323f-752c-b195-e64b08589c67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019fed21-323f-7b4a-a5f3-8a4900e0063e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fed21-323f-7977-b8ed-1c7c6c41f7c2" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019fed21-323f-7b4a-a5f3-8a4900e0063e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fed21-323f-7b4a-a5f3-8a4900e0063e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019fed21-323f-7b4a-a5f3-8a4900e0063e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fed21-323f-7b4a-a5f3-8a4900e0063e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fed21-323f-785c-89c0-b4fc9d92d9ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019fed21-323f-7b4a-a5f3-8a4900e0063e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fed21-323f-785c-89c0-b4fc9d92d9ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019fed21-323f-7e04-b23f-bfc4a2d35c93" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fed21-323f-785c-89c0-b4fc9d92d9ea" xlink:to="loc_us-gaap_SecuredDebtMember_019fed21-323f-7e04-b23f-bfc4a2d35c93" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019fed21-323f-7f58-ac96-863c0cdd943c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fed21-323f-785c-89c0-b4fc9d92d9ea" xlink:to="loc_us-gaap_SeniorNotesMember_019fed21-323f-7f58-ac96-863c0cdd943c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019fed21-323f-7022-8a70-a68915fdbd50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fed21-323f-7977-b8ed-1c7c6c41f7c2" xlink:to="loc_us-gaap_CreditFacilityAxis_019fed21-323f-7022-8a70-a68915fdbd50" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019fed21-323f-7022-8a70-a68915fdbd50_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019fed21-323f-7022-8a70-a68915fdbd50" xlink:to="loc_us-gaap_CreditFacilityDomain_019fed21-323f-7022-8a70-a68915fdbd50_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019fed21-323f-75d3-bb90-87e78cea0f25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019fed21-323f-7022-8a70-a68915fdbd50" xlink:to="loc_us-gaap_CreditFacilityDomain_019fed21-323f-75d3-bb90-87e78cea0f25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019fed21-323f-7b11-8544-419316c06f1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019fed21-323f-75d3-bb90-87e78cea0f25" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019fed21-323f-7b11-8544-419316c06f1d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019fed21-323f-7e95-bc5d-dd0e51a00110" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-77d2-8653-e9a209bfd927" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019fed21-323f-7e95-bc5d-dd0e51a00110" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityIncreaseDecreaseForPeriodNet_019fed21-323f-7c4a-89ee-e1f510b3527e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityIncreaseDecreaseForPeriodNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-77d2-8653-e9a209bfd927" xlink:to="loc_us-gaap_LineOfCreditFacilityIncreaseDecreaseForPeriodNet_019fed21-323f-7c4a-89ee-e1f510b3527e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_019fed21-323f-77c3-b98e-6f135ea79a79" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRepurchasedFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-77d2-8653-e9a209bfd927" xlink:to="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_019fed21-323f-77c3-b98e-6f135ea79a79" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebt_019fed21-323f-76fa-8196-12c0614206bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-77d2-8653-e9a209bfd927" xlink:to="loc_us-gaap_RepaymentsOfDebt_019fed21-323f-76fa-8196-12c0614206bc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_RepaymentOfDebtAccruedInterest_019fed21-323f-7c78-8fe5-de5f7e7f434f" xlink:href="zi-20260930.xsd#zi_RepaymentOfDebtAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-77d2-8653-e9a209bfd927" xlink:to="loc_zi_RepaymentOfDebtAccruedInterest_019fed21-323f-7c78-8fe5-de5f7e7f434f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019fed21-323f-7c48-ba5b-6521d4d36118" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fed21-323f-77d2-8653-e9a209bfd927" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019fed21-323f-7c48-ba5b-6521d4d36118" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesOutstandingInterestRateDerivativesDesignatedasCashFlowHedgesofInterestRateRiskDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#DerivativesandHedgingActivitiesOutstandingInterestRateDerivativesDesignatedasCashFlowHedgesofInterestRateRiskDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesOutstandingInterestRateDerivativesDesignatedasCashFlowHedgesofInterestRateRiskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7ddd-b62f-ab2d8f2a63ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7af8-8a59-96754aa0b60f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7ddd-b62f-ab2d8f2a63ae" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7af8-8a59-96754aa0b60f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-797c-a826-b6209afa1212" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7af8-8a59-96754aa0b60f" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-797c-a826-b6209afa1212" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-797c-a826-b6209afa1212_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-797c-a826-b6209afa1212" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-797c-a826-b6209afa1212_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7483-8a49-423f978ad9aa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-797c-a826-b6209afa1212" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7483-8a49-423f978ad9aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019fed21-32ee-7966-b40e-3da3dbc51944" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7483-8a49-423f978ad9aa" xlink:to="loc_us-gaap_InterestRateSwapMember_019fed21-32ee-7966-b40e-3da3dbc51944" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019fed21-32ee-769d-a141-c5c48af1c3d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7af8-8a59-96754aa0b60f" xlink:to="loc_us-gaap_HedgingDesignationAxis_019fed21-32ee-769d-a141-c5c48af1c3d5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-769d-a141-c5c48af1c3d5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019fed21-32ee-769d-a141-c5c48af1c3d5" xlink:to="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-769d-a141-c5c48af1c3d5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7ba7-b6b7-0f4b409f0a93" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019fed21-32ee-769d-a141-c5c48af1c3d5" xlink:to="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7ba7-b6b7-0f4b409f0a93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019fed21-32ee-7828-8c5b-5fcae71b75a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7ba7-b6b7-0f4b409f0a93" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019fed21-32ee-7828-8c5b-5fcae71b75a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019fed21-32ee-7699-8058-6ac7254c93b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7af8-8a59-96754aa0b60f" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019fed21-32ee-7699-8058-6ac7254c93b1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-7699-8058-6ac7254c93b1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019fed21-32ee-7699-8058-6ac7254c93b1" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-7699-8058-6ac7254c93b1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-73b1-9260-71ff0421a2a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019fed21-32ee-7699-8058-6ac7254c93b1" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-73b1-9260-71ff0421a2a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_019fed21-32ee-72b8-b284-50a4dbe6268c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-73b1-9260-71ff0421a2a9" xlink:to="loc_us-gaap_CashFlowHedgingMember_019fed21-32ee-72b8-b284-50a4dbe6268c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_019fed21-32ee-7983-ab09-3d6a9230bdaa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNumberOfInstrumentsHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7ddd-b62f-ab2d8f2a63ae" xlink:to="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_019fed21-32ee-7983-ab09-3d6a9230bdaa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019fed21-32ee-7bee-9f8e-3314059a779b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7ddd-b62f-ab2d8f2a63ae" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019fed21-32ee-7bee-9f8e-3314059a779b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAverageFixedInterestRate_019fed21-32ee-7633-ab58-d5b96da55d92" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAverageFixedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7ddd-b62f-ab2d8f2a63ae" xlink:to="loc_us-gaap_DerivativeAverageFixedInterestRate_019fed21-32ee-7633-ab58-d5b96da55d92" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesNarrativeDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#DerivativesandHedgingActivitiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019fed21-32ee-7cd9-aae1-c287278cd12c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019fed21-32ee-701e-8433-9842275bb5e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019fed21-32ee-7cd9-aae1-c287278cd12c" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019fed21-32ee-701e-8433-9842275bb5e0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7eaf-9a64-0e95d679385b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019fed21-32ee-701e-8433-9842275bb5e0" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7eaf-9a64-0e95d679385b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7eaf-9a64-0e95d679385b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7eaf-9a64-0e95d679385b" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7eaf-9a64-0e95d679385b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7882-9839-18e9cfe91df2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7eaf-9a64-0e95d679385b" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7882-9839-18e9cfe91df2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019fed21-32ee-7009-91e5-6143137afdaa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7882-9839-18e9cfe91df2" xlink:to="loc_us-gaap_InterestRateSwapMember_019fed21-32ee-7009-91e5-6143137afdaa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_019fed21-32ee-7385-a2ca-51b029c47b17" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019fed21-32ee-7cd9-aae1-c287278cd12c" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_019fed21-32ee-7385-a2ca-51b029c47b17" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesFairValueandPresentationintheConsolidatedBalanceSheetsforDerivativesDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#DerivativesandHedgingActivitiesFairValueandPresentationintheConsolidatedBalanceSheetsforDerivativesDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesFairValueandPresentationintheConsolidatedBalanceSheetsforDerivativesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7838-a808-892c3b4fb3d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7b00-a28e-0411527ae408" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7838-a808-892c3b4fb3d2" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7b00-a28e-0411527ae408" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019fed21-32ee-7690-af25-0bd768e3bdf2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7b00-a28e-0411527ae408" xlink:to="loc_us-gaap_HedgingDesignationAxis_019fed21-32ee-7690-af25-0bd768e3bdf2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7690-af25-0bd768e3bdf2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019fed21-32ee-7690-af25-0bd768e3bdf2" xlink:to="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7690-af25-0bd768e3bdf2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7978-bb1e-e83e7a04ca69" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019fed21-32ee-7690-af25-0bd768e3bdf2" xlink:to="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7978-bb1e-e83e7a04ca69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019fed21-32ee-73a0-ae7b-520b4339a129" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7978-bb1e-e83e7a04ca69" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019fed21-32ee-73a0-ae7b-520b4339a129" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019fed21-32ee-774f-9648-9df6f04f0741" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7b00-a28e-0411527ae408" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019fed21-32ee-774f-9648-9df6f04f0741" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-774f-9648-9df6f04f0741_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019fed21-32ee-774f-9648-9df6f04f0741" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-774f-9648-9df6f04f0741_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-7b8f-a2e2-f7ae98029dc1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019fed21-32ee-774f-9648-9df6f04f0741" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-7b8f-a2e2-f7ae98029dc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_019fed21-32ee-7183-916d-37cb9f67a9b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-7b8f-a2e2-f7ae98029dc1" xlink:to="loc_us-gaap_CashFlowHedgingMember_019fed21-32ee-7183-916d-37cb9f67a9b0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019fed21-32ee-774a-a28d-bf3641de1dd5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfFinancialPositionLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7b00-a28e-0411527ae408" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019fed21-32ee-774a-a28d-bf3641de1dd5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7572-b29e-9546b7d2ffbb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7b00-a28e-0411527ae408" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7572-b29e-9546b7d2ffbb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7572-b29e-9546b7d2ffbb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7572-b29e-9546b7d2ffbb" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7572-b29e-9546b7d2ffbb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-791e-825a-a7092c54d2a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7572-b29e-9546b7d2ffbb" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-791e-825a-a7092c54d2a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019fed21-32ee-7086-ae84-7fb7385e004b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-791e-825a-a7092c54d2a5" xlink:to="loc_us-gaap_InterestRateSwapMember_019fed21-32ee-7086-ae84-7fb7385e004b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019fed21-32ee-7935-a549-41e724c15fa0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7838-a808-892c3b4fb3d2" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019fed21-32ee-7935-a549-41e724c15fa0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019fed21-32ee-79a6-9237-ee6c96088ca4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7838-a808-892c3b4fb3d2" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019fed21-32ee-79a6-9237-ee6c96088ca4" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesFairValueandPresentationintheConsolidatedBalanceSheetsforDerivativesDetails_1" xlink:type="simple" xlink:href="zi-20260930.xsd#DerivativesandHedgingActivitiesFairValueandPresentationintheConsolidatedBalanceSheetsforDerivativesDetails_1"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/DerivativesandHedgingActivitiesFairValueandPresentationintheConsolidatedBalanceSheetsforDerivativesDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7838-a808-892c3b4fb3d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7b00-a28e-0411527ae408" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7838-a808-892c3b4fb3d2" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7b00-a28e-0411527ae408" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019fed21-32ee-7690-af25-0bd768e3bdf2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7b00-a28e-0411527ae408" xlink:to="loc_us-gaap_HedgingDesignationAxis_019fed21-32ee-7690-af25-0bd768e3bdf2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7690-af25-0bd768e3bdf2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019fed21-32ee-7690-af25-0bd768e3bdf2" xlink:to="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7690-af25-0bd768e3bdf2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7978-bb1e-e83e7a04ca69" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019fed21-32ee-7690-af25-0bd768e3bdf2" xlink:to="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7978-bb1e-e83e7a04ca69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019fed21-32ee-73a0-ae7b-520b4339a129" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019fed21-32ee-7978-bb1e-e83e7a04ca69" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019fed21-32ee-73a0-ae7b-520b4339a129" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019fed21-32ee-774f-9648-9df6f04f0741" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7b00-a28e-0411527ae408" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019fed21-32ee-774f-9648-9df6f04f0741" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-774f-9648-9df6f04f0741_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019fed21-32ee-774f-9648-9df6f04f0741" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-774f-9648-9df6f04f0741_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-7b8f-a2e2-f7ae98029dc1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019fed21-32ee-774f-9648-9df6f04f0741" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-7b8f-a2e2-f7ae98029dc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_019fed21-32ee-7183-916d-37cb9f67a9b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019fed21-32ee-7b8f-a2e2-f7ae98029dc1" xlink:to="loc_us-gaap_CashFlowHedgingMember_019fed21-32ee-7183-916d-37cb9f67a9b0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7572-b29e-9546b7d2ffbb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019fed21-32ee-7b00-a28e-0411527ae408" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7572-b29e-9546b7d2ffbb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7572-b29e-9546b7d2ffbb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7572-b29e-9546b7d2ffbb" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7572-b29e-9546b7d2ffbb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-791e-825a-a7092c54d2a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7572-b29e-9546b7d2ffbb" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-791e-825a-a7092c54d2a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019fed21-32ee-7086-ae84-7fb7385e004b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-791e-825a-a7092c54d2a5" xlink:to="loc_us-gaap_InterestRateSwapMember_019fed21-32ee-7086-ae84-7fb7385e004b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019fed21-32ee-7935-a549-41e724c15fa0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7838-a808-892c3b4fb3d2" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019fed21-32ee-7935-a549-41e724c15fa0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019fed21-32ee-79a6-9237-ee6c96088ca4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019fed21-32ee-7838-a808-892c3b4fb3d2" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019fed21-32ee-79a6-9237-ee6c96088ca4" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/FairValueNarrativeDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#FairValueNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/FairValueNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fed21-32ee-7bbc-a7df-ce6a1ea21f9a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fed21-32ee-73a5-838b-670fef9d411a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fed21-32ee-7bbc-a7df-ce6a1ea21f9a" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fed21-32ee-73a5-838b-670fef9d411a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019fed21-32ee-7564-958e-82bae8491dcc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fed21-32ee-73a5-838b-670fef9d411a" xlink:to="loc_us-gaap_DebtInstrumentAxis_019fed21-32ee-7564-958e-82bae8491dcc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fed21-32ee-7564-958e-82bae8491dcc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fed21-32ee-7564-958e-82bae8491dcc" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fed21-32ee-7564-958e-82bae8491dcc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fed21-32ee-73f9-802f-f85e915c5e44" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fed21-32ee-7564-958e-82bae8491dcc" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fed21-32ee-73f9-802f-f85e915c5e44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_FirstLienTermLoanMember_019fed21-32ee-717c-bef5-43f2f1c98d5d" xlink:href="zi-20260930.xsd#zi_FirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fed21-32ee-73f9-802f-f85e915c5e44" xlink:to="loc_zi_FirstLienTermLoanMember_019fed21-32ee-717c-bef5-43f2f1c98d5d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_A3875SeniorNotesMember_019fed21-32ee-7801-9d80-fa4671c84f12" xlink:href="zi-20260930.xsd#zi_A3875SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fed21-32ee-73f9-802f-f85e915c5e44" xlink:to="loc_zi_A3875SeniorNotesMember_019fed21-32ee-7801-9d80-fa4671c84f12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fed21-32ee-7563-9128-f0b51e7c3bc6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fed21-32ee-73a5-838b-670fef9d411a" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fed21-32ee-7563-9128-f0b51e7c3bc6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fed21-32ee-7563-9128-f0b51e7c3bc6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fed21-32ee-7563-9128-f0b51e7c3bc6" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fed21-32ee-7563-9128-f0b51e7c3bc6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fed21-32ee-7e91-99f3-64ac1e42bd4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fed21-32ee-7563-9128-f0b51e7c3bc6" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fed21-32ee-7e91-99f3-64ac1e42bd4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019fed21-32ee-7d08-9d44-392f332c1f28" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fed21-32ee-7e91-99f3-64ac1e42bd4f" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019fed21-32ee-7d08-9d44-392f332c1f28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019fed21-32ee-757a-a9ad-28634dcc3c53" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fed21-32ee-73a5-838b-670fef9d411a" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019fed21-32ee-757a-a9ad-28634dcc3c53" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fed21-32ee-757a-a9ad-28634dcc3c53_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019fed21-32ee-757a-a9ad-28634dcc3c53" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fed21-32ee-757a-a9ad-28634dcc3c53_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019fed21-32ee-7ab6-8d3f-7712b34c399c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019fed21-32ee-757a-a9ad-28634dcc3c53" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019fed21-32ee-7ab6-8d3f-7712b34c399c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019fed21-32ee-77e7-b607-1b35e618b36a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fed21-32ee-7ab6-8d3f-7712b34c399c" xlink:to="loc_us-gaap_SecuredDebtMember_019fed21-32ee-77e7-b607-1b35e618b36a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019fed21-32ee-7203-9a39-dca975580b8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019fed21-32ee-7ab6-8d3f-7712b34c399c" xlink:to="loc_us-gaap_SeniorNotesMember_019fed21-32ee-7203-9a39-dca975580b8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_019fed21-32ee-7202-9a8a-35298b867307" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fed21-32ee-7bbc-a7df-ce6a1ea21f9a" xlink:to="loc_us-gaap_DebtInstrumentFairValue_019fed21-32ee-7202-9a8a-35298b867307" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/FairValueFinancialAssetsDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#FairValueFinancialAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/FairValueFinancialAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fed21-32ee-79c7-bb0e-3bd01542c272" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fed21-32ee-7a92-bad3-2aa85200f83f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fed21-32ee-79c7-bb0e-3bd01542c272" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fed21-32ee-7a92-bad3-2aa85200f83f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fed21-32ee-78b4-9f64-c7c2c6f8cd41" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fed21-32ee-7a92-bad3-2aa85200f83f" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fed21-32ee-78b4-9f64-c7c2c6f8cd41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fed21-32ee-78b4-9f64-c7c2c6f8cd41_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fed21-32ee-78b4-9f64-c7c2c6f8cd41" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fed21-32ee-78b4-9f64-c7c2c6f8cd41_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fed21-32ee-7f97-b9f4-7ac372ae44d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fed21-32ee-78b4-9f64-c7c2c6f8cd41" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fed21-32ee-7f97-b9f4-7ac372ae44d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019fed21-32ee-74ab-8de3-61e9364480b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fed21-32ee-7f97-b9f4-7ac372ae44d5" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019fed21-32ee-74ab-8de3-61e9364480b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019fed21-32ee-7c5a-80f7-475a1c1d52de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fed21-32ee-7f97-b9f4-7ac372ae44d5" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019fed21-32ee-7c5a-80f7-475a1c1d52de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019fed21-32ee-72a4-b378-bce9d9b778d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fed21-32ee-7f97-b9f4-7ac372ae44d5" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019fed21-32ee-72a4-b378-bce9d9b778d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019fed21-32ee-7713-b8dc-8fe809a80db8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fed21-32ee-7a92-bad3-2aa85200f83f" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019fed21-32ee-7713-b8dc-8fe809a80db8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019fed21-32ee-7713-b8dc-8fe809a80db8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019fed21-32ee-7713-b8dc-8fe809a80db8" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019fed21-32ee-7713-b8dc-8fe809a80db8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019fed21-32ee-7708-9781-c6a8b5fb1ee0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019fed21-32ee-7713-b8dc-8fe809a80db8" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019fed21-32ee-7708-9781-c6a8b5fb1ee0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019fed21-32ee-7fbe-8cc2-d4004d98f07e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019fed21-32ee-7708-9781-c6a8b5fb1ee0" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019fed21-32ee-7fbe-8cc2-d4004d98f07e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsNonrecurringMember_019fed21-32ee-7d6b-9c4d-e27e969a246e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsNonrecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019fed21-32ee-7708-9781-c6a8b5fb1ee0" xlink:to="loc_us-gaap_FairValueMeasurementsNonrecurringMember_019fed21-32ee-7d6b-9c4d-e27e969a246e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7c95-8cc3-2dd29233a1e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fed21-32ee-7a92-bad3-2aa85200f83f" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7c95-8cc3-2dd29233a1e5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7c95-8cc3-2dd29233a1e5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7c95-8cc3-2dd29233a1e5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-7c95-8cc3-2dd29233a1e5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-78f0-8dc5-01f4a3ea82a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019fed21-32ee-7c95-8cc3-2dd29233a1e5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-78f0-8dc5-01f4a3ea82a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019fed21-32ee-7160-87e0-093913258fc0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019fed21-32ee-78f0-8dc5-01f4a3ea82a4" xlink:to="loc_us-gaap_InterestRateSwapMember_019fed21-32ee-7160-87e0-093913258fc0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019fed21-32ee-793e-b5b3-92776eba4da2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fed21-32ee-7a92-bad3-2aa85200f83f" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019fed21-32ee-793e-b5b3-92776eba4da2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-32ee-793e-b5b3-92776eba4da2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fed21-32ee-793e-b5b3-92776eba4da2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-32ee-793e-b5b3-92776eba4da2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-32ee-79bd-8dcd-4b4173b58e1e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fed21-32ee-793e-b5b3-92776eba4da2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-32ee-79bd-8dcd-4b4173b58e1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CertificatesOfDepositMember_019fed21-32ee-7a61-888a-776cad24a746" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CertificatesOfDepositMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-32ee-79bd-8dcd-4b4173b58e1e" xlink:to="loc_us-gaap_CertificatesOfDepositMember_019fed21-32ee-7a61-888a-776cad24a746" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_019fed21-32ee-77e0-af40-71bbd2c3524d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-32ee-79bd-8dcd-4b4173b58e1e" xlink:to="loc_us-gaap_MoneyMarketFundsMember_019fed21-32ee-77e0-af40-71bbd2c3524d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_019fed21-32ee-7f8f-a51c-f802a1bf18c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-32ee-79bd-8dcd-4b4173b58e1e" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_019fed21-32ee-7f8f-a51c-f802a1bf18c1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_019fed21-32ee-7773-a628-66aaf0a703fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fed21-32ee-79bd-8dcd-4b4173b58e1e" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_019fed21-32ee-7773-a628-66aaf0a703fa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fed21-32ee-7332-9761-a01dac076c1f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fed21-32ee-79c7-bb0e-3bd01542c272" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fed21-32ee-7332-9761-a01dac076c1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashEquivalentsAtCarryingValue_019fed21-32ee-7464-8fbc-1171b6c0fc33" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fed21-32ee-7332-9761-a01dac076c1f" xlink:to="loc_us-gaap_CashEquivalentsAtCarryingValue_019fed21-32ee-7464-8fbc-1171b6c0fc33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019fed21-32ee-7f38-8abd-6daaf76edb10" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fed21-32ee-7332-9761-a01dac076c1f" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019fed21-32ee-7f38-8abd-6daaf76edb10" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019fed21-32ee-70af-a217-2e4d2ea6fd3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fed21-32ee-7332-9761-a01dac076c1f" xlink:to="loc_us-gaap_DerivativeAssets_019fed21-32ee-70af-a217-2e4d2ea6fd3c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_019fed21-32ee-7e3d-a940-f36207450a7f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fed21-32ee-7332-9761-a01dac076c1f" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_019fed21-32ee-7e3d-a940-f36207450a7f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019fed21-32ee-7cc0-bd50-07f9967a33b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fed21-32ee-7332-9761-a01dac076c1f" xlink:to="loc_us-gaap_Goodwill_019fed21-32ee-7cc0-bd50-07f9967a33b3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019fed21-32ee-76d1-8a7a-747706148f2f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fed21-32ee-7332-9761-a01dac076c1f" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_019fed21-32ee-76d1-8a7a-747706148f2f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_019fed21-32ee-7e84-9def-90f7f9ed0298" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019fed21-32ee-7332-9761-a01dac076c1f" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_019fed21-32ee-7e84-9def-90f7f9ed0298" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/CommitmentsandContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RecordedUnconditionalPurchaseObligationLineItems_019fed21-32ee-7852-9046-05d4cd03336d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RecordedUnconditionalPurchaseObligationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RecordedUnconditionalPurchaseObligationTable_019fed21-32ee-76ea-9f43-38d8280d6759" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RecordedUnconditionalPurchaseObligationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RecordedUnconditionalPurchaseObligationLineItems_019fed21-32ee-7852-9046-05d4cd03336d" xlink:to="loc_us-gaap_RecordedUnconditionalPurchaseObligationTable_019fed21-32ee-76ea-9f43-38d8280d6759" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_01a17b4e-9f79-752d-b0e1-724dc418e04f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RecordedUnconditionalPurchaseObligationTable_019fed21-32ee-76ea-9f43-38d8280d6759" xlink:to="loc_srt_LitigationCaseAxis_01a17b4e-9f79-752d-b0e1-724dc418e04f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_01a17b4e-9f79-752d-b0e1-724dc418e04f_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_01a17b4e-9f79-752d-b0e1-724dc418e04f" xlink:to="loc_srt_LitigationCaseTypeDomain_01a17b4e-9f79-752d-b0e1-724dc418e04f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_01a17b4e-9f79-76ed-b1f9-d82c6a2b08de" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_01a17b4e-9f79-752d-b0e1-724dc418e04f" xlink:to="loc_srt_LitigationCaseTypeDomain_01a17b4e-9f79-76ed-b1f9-d82c6a2b08de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_A2024SecuritiesLitigationMember_01a17b4f-1447-7f32-b96f-865e34d30c31" xlink:href="zi-20260930.xsd#zi_A2024SecuritiesLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_01a17b4e-9f79-76ed-b1f9-d82c6a2b08de" xlink:to="loc_zi_A2024SecuritiesLitigationMember_01a17b4f-1447-7f32-b96f-865e34d30c31" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_01a17b4f-87da-71be-8786-30c71110649a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RecordedUnconditionalPurchaseObligationTable_019fed21-32ee-76ea-9f43-38d8280d6759" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_01a17b4f-87da-71be-8786-30c71110649a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_01a17b4f-87da-71be-8786-30c71110649a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_01a17b4f-87da-71be-8786-30c71110649a" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_01a17b4f-87da-71be-8786-30c71110649a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_01a17b4f-87da-7f62-b11e-d1371fb69dd8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_01a17b4f-87da-71be-8786-30c71110649a" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_01a17b4f-87da-7f62-b11e-d1371fb69dd8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_01a17b4f-a359-7a25-a74c-0f0960764cdb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_01a17b4f-87da-7f62-b11e-d1371fb69dd8" xlink:to="loc_us-gaap_SubsequentEventMember_01a17b4f-a359-7a25-a74c-0f0960764cdb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_01a17b4e-6f2e-7c61-abc3-6580e216628c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RecordedUnconditionalPurchaseObligationLineItems_019fed21-32ee-7852-9046-05d4cd03336d" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_01a17b4e-6f2e-7c61-abc3-6580e216628c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationReserve_01a17b51-32b2-77ef-ba99-31c69c96be9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RecordedUnconditionalPurchaseObligationLineItems_019fed21-32ee-7852-9046-05d4cd03336d" xlink:to="loc_us-gaap_LitigationReserve_01a17b51-32b2-77ef-ba99-31c69c96be9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivable_01a17b52-ee1a-715f-94b7-79be77084bb8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RecordedUnconditionalPurchaseObligationLineItems_019fed21-32ee-7852-9046-05d4cd03336d" xlink:to="loc_us-gaap_LossContingencyReceivable_01a17b52-ee1a-715f-94b7-79be77084bb8" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EarningsLossPerSharePotentialCommonStockEquivalentsExcludedfromCalculationofDilutedNetIncomePerShareDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#EarningsLossPerSharePotentialCommonStockEquivalentsExcludedfromCalculationofDilutedNetIncomePerShareDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EarningsLossPerSharePotentialCommonStockEquivalentsExcludedfromCalculationofDilutedNetIncomePerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fed21-32ee-7dc4-9e97-b02bf0093336" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019fed21-32ee-72de-8ef4-56e5eae5be63" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fed21-32ee-7dc4-9e97-b02bf0093336" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019fed21-32ee-72de-8ef4-56e5eae5be63" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019fed21-32ee-76ce-9761-cecebe838907" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019fed21-32ee-72de-8ef4-56e5eae5be63" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019fed21-32ee-76ce-9761-cecebe838907" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fed21-32ee-76ce-9761-cecebe838907_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019fed21-32ee-76ce-9761-cecebe838907" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fed21-32ee-76ce-9761-cecebe838907_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fed21-32ee-7619-a914-b3393b4c6d73" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019fed21-32ee-76ce-9761-cecebe838907" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fed21-32ee-7619-a914-b3393b4c6d73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019fed21-32ee-786a-abf4-f8b6ff777524" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fed21-32ee-7619-a914-b3393b4c6d73" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019fed21-32ee-786a-abf4-f8b6ff777524" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_EmployeeStockPurchasePlanMember_01a17b62-3633-7aab-a07a-8c4bf51ebc65" xlink:href="zi-20260930.xsd#zi_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fed21-32ee-7619-a914-b3393b4c6d73" xlink:to="loc_zi_EmployeeStockPurchasePlanMember_01a17b62-3633-7aab-a07a-8c4bf51ebc65" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_CEOPremiumPricedPerformanceOptionMember_019fed21-32ee-7d29-86be-67e10c08b607" xlink:href="zi-20260930.xsd#zi_CEOPremiumPricedPerformanceOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fed21-32ee-7619-a914-b3393b4c6d73" xlink:to="loc_zi_CEOPremiumPricedPerformanceOptionMember_019fed21-32ee-7d29-86be-67e10c08b607" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_LiabilityClassifiedAwardsMember_019fed21-32ee-76ef-93d4-ccca39e401ab" xlink:href="zi-20260930.xsd#zi_LiabilityClassifiedAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fed21-32ee-7619-a914-b3393b4c6d73" xlink:to="loc_zi_LiabilityClassifiedAwardsMember_019fed21-32ee-76ef-93d4-ccca39e401ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019fed21-32ee-7c11-ad9a-9ffe0e304755" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fed21-32ee-7619-a914-b3393b4c6d73" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019fed21-32ee-7c11-ad9a-9ffe0e304755" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019fed21-32ee-7934-9800-4d6e8ed994bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fed21-32ee-7dc4-9e97-b02bf0093336" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019fed21-32ee-7934-9800-4d6e8ed994bd" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#LeasesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/LeasesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorLeaseDescriptionLineItems_019fed21-32ee-7b0f-b085-a8d252624dc5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LessorLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorLeaseDescriptionTable_019fed21-32ee-7874-9717-c5efa6c671e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LessorLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_019fed21-32ee-7b0f-b085-a8d252624dc5" xlink:to="loc_us-gaap_LessorLeaseDescriptionTable_019fed21-32ee-7874-9717-c5efa6c671e8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019fed21-32ee-7638-9ef2-86fa87ddd8db" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LessorLeaseDescriptionTable_019fed21-32ee-7874-9717-c5efa6c671e8" xlink:to="loc_srt_CounterpartyNameAxis_019fed21-32ee-7638-9ef2-86fa87ddd8db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fed21-32ee-7638-9ef2-86fa87ddd8db_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019fed21-32ee-7638-9ef2-86fa87ddd8db" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fed21-32ee-7638-9ef2-86fa87ddd8db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fed21-32ee-7584-9a7d-847ef21c18b4" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019fed21-32ee-7638-9ef2-86fa87ddd8db" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fed21-32ee-7584-9a7d-847ef21c18b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_LeaseRestructuringActivitiesMember_019fed21-32ee-7177-bc57-7558e88181bd" xlink:href="zi-20260930.xsd#zi_LeaseRestructuringActivitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fed21-32ee-7584-9a7d-847ef21c18b4" xlink:to="loc_zi_LeaseRestructuringActivitiesMember_019fed21-32ee-7177-bc57-7558e88181bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019fed21-32ee-7d53-8f98-fa49067803b3" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LessorLeaseDescriptionTable_019fed21-32ee-7874-9717-c5efa6c671e8" xlink:to="loc_srt_StatementGeographicalAxis_019fed21-32ee-7d53-8f98-fa49067803b3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019fed21-32ee-7d53-8f98-fa49067803b3_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019fed21-32ee-7d53-8f98-fa49067803b3" xlink:to="loc_srt_SegmentGeographicalDomain_019fed21-32ee-7d53-8f98-fa49067803b3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019fed21-32ee-7cee-8990-8f38e02c90ad" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019fed21-32ee-7d53-8f98-fa49067803b3" xlink:to="loc_srt_SegmentGeographicalDomain_019fed21-32ee-7cee-8990-8f38e02c90ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_RaananaIsraelMember_019fed21-32ee-74bf-a81f-7c35db32e575" xlink:href="zi-20260930.xsd#zi_RaananaIsraelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019fed21-32ee-7cee-8990-8f38e02c90ad" xlink:to="loc_zi_RaananaIsraelMember_019fed21-32ee-74bf-a81f-7c35db32e575" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_WalthamMassachusettsMember_019fed21-32ee-788b-982d-8d74b18a9c13" xlink:href="zi-20260930.xsd#zi_WalthamMassachusettsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019fed21-32ee-7cee-8990-8f38e02c90ad" xlink:to="loc_zi_WalthamMassachusettsMember_019fed21-32ee-788b-982d-8d74b18a9c13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseExpense_019fed21-32ee-7fd8-b071-743d4c0560f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_019fed21-32ee-7b0f-b085-a8d252624dc5" xlink:to="loc_us-gaap_OperatingLeaseExpense_019fed21-32ee-7fd8-b071-743d4c0560f1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments_019fed21-32ee-7677-bd6e-d3950cbf3d1c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_019fed21-32ee-7b0f-b085-a8d252624dc5" xlink:to="loc_us-gaap_OperatingLeasePayments_019fed21-32ee-7677-bd6e-d3950cbf3d1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseImpairmentLoss_019fed21-32ee-7b1b-b348-5398259deb08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_019fed21-32ee-7b0f-b085-a8d252624dc5" xlink:to="loc_us-gaap_OperatingLeaseImpairmentLoss_019fed21-32ee-7b1b-b348-5398259deb08" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_019fed21-32ee-7a0a-a812-a83ce698f59c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_019fed21-32ee-7b0f-b085-a8d252624dc5" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_019fed21-32ee-7a0a-a812-a83ce698f59c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_GainLossOnLeaseModification_019fed21-32ee-7679-8445-836d00f6baff" xlink:href="zi-20260930.xsd#zi_GainLossOnLeaseModification"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_019fed21-32ee-7b0f-b085-a8d252624dc5" xlink:to="loc_zi_GainLossOnLeaseModification_019fed21-32ee-7679-8445-836d00f6baff" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_IncreaseDecreaseInOperatingLeasesFutureMinimumPayments_019fed21-32ee-7269-909c-6e121bae394f" xlink:href="zi-20260930.xsd#zi_IncreaseDecreaseInOperatingLeasesFutureMinimumPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_019fed21-32ee-7b0f-b085-a8d252624dc5" xlink:to="loc_zi_IncreaseDecreaseInOperatingLeasesFutureMinimumPayments_019fed21-32ee-7269-909c-6e121bae394f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_OperatingLeaseRightOfUseAssetLeaseAbandonmentCharge_019fed21-32ee-7bcd-aff4-a52164859580" xlink:href="zi-20260930.xsd#zi_OperatingLeaseRightOfUseAssetLeaseAbandonmentCharge"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_019fed21-32ee-7b0f-b085-a8d252624dc5" xlink:to="loc_zi_OperatingLeaseRightOfUseAssetLeaseAbandonmentCharge_019fed21-32ee-7bcd-aff4-a52164859580" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/LeasesOtherInformationRelatedtoLeasesDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#LeasesOtherInformationRelatedtoLeasesDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/LeasesOtherInformationRelatedtoLeasesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019fed21-32ee-7c25-acee-ae04012dfb56" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019fed21-32ee-7fec-a9a2-cc0cbeb18415" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019fed21-32ee-7c25-acee-ae04012dfb56" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019fed21-32ee-7fec-a9a2-cc0cbeb18415" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseContractualTermAxis_019fed21-32ee-7e05-a9a6-842154cf10fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LeaseContractualTermAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019fed21-32ee-7fec-a9a2-cc0cbeb18415" xlink:to="loc_us-gaap_LeaseContractualTermAxis_019fed21-32ee-7e05-a9a6-842154cf10fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseContractualTermDomain_019fed21-32ee-7e05-a9a6-842154cf10fd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LeaseContractualTermDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LeaseContractualTermAxis_019fed21-32ee-7e05-a9a6-842154cf10fd" xlink:to="loc_us-gaap_LeaseContractualTermDomain_019fed21-32ee-7e05-a9a6-842154cf10fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseContractualTermDomain_019fed21-32ee-7d89-9aaf-80b07885eb32" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LeaseContractualTermDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LeaseContractualTermAxis_019fed21-32ee-7e05-a9a6-842154cf10fd" xlink:to="loc_us-gaap_LeaseContractualTermDomain_019fed21-32ee-7d89-9aaf-80b07885eb32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_NewAndExistingLeaseAgreementsMember_019fed21-32ee-74a8-8c22-361c1ea91374" xlink:href="zi-20260930.xsd#zi_NewAndExistingLeaseAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LeaseContractualTermDomain_019fed21-32ee-7d89-9aaf-80b07885eb32" xlink:to="loc_zi_NewAndExistingLeaseAgreementsMember_019fed21-32ee-74a8-8c22-361c1ea91374" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019fed21-32ee-75eb-9d5e-1fb07d512950" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019fed21-32ee-7fec-a9a2-cc0cbeb18415" xlink:to="loc_srt_StatementGeographicalAxis_019fed21-32ee-75eb-9d5e-1fb07d512950" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019fed21-32ee-75eb-9d5e-1fb07d512950_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019fed21-32ee-75eb-9d5e-1fb07d512950" xlink:to="loc_srt_SegmentGeographicalDomain_019fed21-32ee-75eb-9d5e-1fb07d512950_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019fed21-32ee-7662-967c-b25b8879f215" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019fed21-32ee-75eb-9d5e-1fb07d512950" xlink:to="loc_srt_SegmentGeographicalDomain_019fed21-32ee-7662-967c-b25b8879f215" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_RaananaIsraelMember_019fed21-32ee-7b9e-ba2f-6cf86ee69080" xlink:href="zi-20260930.xsd#zi_RaananaIsraelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019fed21-32ee-7662-967c-b25b8879f215" xlink:to="loc_zi_RaananaIsraelMember_019fed21-32ee-7b9e-ba2f-6cf86ee69080" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments_019fed21-32ee-7a74-be62-e3480761a4fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019fed21-32ee-7c25-acee-ae04012dfb56" xlink:to="loc_us-gaap_OperatingLeasePayments_019fed21-32ee-7a74-be62-e3480761a4fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_OperatingLeaseTenantIncentiveReimbursement_019fed21-32ee-76d8-9a71-535ec97a7a48" xlink:href="zi-20260930.xsd#zi_OperatingLeaseTenantIncentiveReimbursement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019fed21-32ee-7c25-acee-ae04012dfb56" xlink:to="loc_zi_OperatingLeaseTenantIncentiveReimbursement_019fed21-32ee-76d8-9a71-535ec97a7a48" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_019fed21-32ee-7862-ac58-d2b6f341b070" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019fed21-32ee-7c25-acee-ae04012dfb56" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_019fed21-32ee-7862-ac58-d2b6f341b070" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#EquitybasedCompensationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-7af9-bd44-3dd4d9256be2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ee-78e6-9de1-f05e2e4abae7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-7af9-bd44-3dd4d9256be2" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ee-78e6-9de1-f05e2e4abae7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019fed21-32ee-70af-90c0-e94a17f45f33" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ee-78e6-9de1-f05e2e4abae7" xlink:to="loc_us-gaap_AwardTypeAxis_019fed21-32ee-70af-90c0-e94a17f45f33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ee-70af-90c0-e94a17f45f33_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019fed21-32ee-70af-90c0-e94a17f45f33" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ee-70af-90c0-e94a17f45f33_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ee-76ed-ab64-5e8e31781184" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019fed21-32ee-70af-90c0-e94a17f45f33" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ee-76ed-ab64-5e8e31781184" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_LiabilityBasedAwardMember_019fed21-32ee-7b19-9d56-7ab5d5f8fbe5" xlink:href="zi-20260930.xsd#zi_LiabilityBasedAwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ee-76ed-ab64-5e8e31781184" xlink:to="loc_zi_LiabilityBasedAwardMember_019fed21-32ee-7b19-9d56-7ab5d5f8fbe5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019fed21-32ef-7eee-a1a0-1726fe082a57" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ee-78e6-9de1-f05e2e4abae7" xlink:to="loc_us-gaap_PlanNameAxis_019fed21-32ef-7eee-a1a0-1726fe082a57" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019fed21-32ef-7eee-a1a0-1726fe082a57_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019fed21-32ef-7eee-a1a0-1726fe082a57" xlink:to="loc_us-gaap_PlanNameDomain_019fed21-32ef-7eee-a1a0-1726fe082a57_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019fed21-32ef-7353-8d69-60a2e41b6aad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019fed21-32ef-7eee-a1a0-1726fe082a57" xlink:to="loc_us-gaap_PlanNameDomain_019fed21-32ef-7353-8d69-60a2e41b6aad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_InducementPlanMember_01a17ef5-da6f-7b92-88fa-433bce84469c" xlink:href="zi-20260930.xsd#zi_InducementPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019fed21-32ef-7353-8d69-60a2e41b6aad" xlink:to="loc_zi_InducementPlanMember_01a17ef5-da6f-7b92-88fa-433bce84469c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_EmployeeStockPurchasePlanMember_019fed21-32ef-7f54-a428-1173eaf72afa" xlink:href="zi-20260930.xsd#zi_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019fed21-32ef-7353-8d69-60a2e41b6aad" xlink:to="loc_zi_EmployeeStockPurchasePlanMember_019fed21-32ef-7f54-a428-1173eaf72afa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_01a17ef5-da6f-7873-b860-d998a6bb948c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-7af9-bd44-3dd4d9256be2" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_01a17ef5-da6f-7873-b860-d998a6bb948c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_01a1188b-868d-7ad0-9cc7-2c58d0ef301d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-7af9-bd44-3dd4d9256be2" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_01a1188b-868d-7ad0-9cc7-2c58d0ef301d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019fed21-32ef-7ca4-ad13-5327900210c4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-7af9-bd44-3dd4d9256be2" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019fed21-32ef-7ca4-ad13-5327900210c4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriodDuration_019fed21-32ef-77e2-859f-dd16d91af361" xlink:href="zi-20260930.xsd#zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriodDuration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-7af9-bd44-3dd4d9256be2" xlink:to="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriodDuration_019fed21-32ef-77e2-859f-dd16d91af361" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfOfferingPeriodsPermitted_019fed21-32ef-776f-a475-3164deb5268d" xlink:href="zi-20260930.xsd#zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfOfferingPeriodsPermitted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-7af9-bd44-3dd4d9256be2" xlink:to="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfOfferingPeriodsPermitted_019fed21-32ef-776f-a475-3164deb5268d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePeriodDuration_019fed21-32ef-7f8a-aca2-588624bfa14c" xlink:href="zi-20260930.xsd#zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePeriodDuration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-7af9-bd44-3dd4d9256be2" xlink:to="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePeriodDuration_019fed21-32ef-7f8a-aca2-588624bfa14c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesPerEmployee_01a17b99-99a7-71b6-9855-12fb9deca0ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesPerEmployee"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-7af9-bd44-3dd4d9256be2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesPerEmployee_01a17b99-99a7-71b6-9855-12fb9deca0ec" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardValueOfSharesWithheldForFuturePurchases_01a17b78-0e03-795a-bed8-b5bbf009b579" xlink:href="zi-20260930.xsd#zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardValueOfSharesWithheldForFuturePurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-7af9-bd44-3dd4d9256be2" xlink:to="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardValueOfSharesWithheldForFuturePurchases_01a17b78-0e03-795a-bed8-b5bbf009b579" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_01a17b7b-6ccf-74ad-9924-a0a5ba906280" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-7af9-bd44-3dd4d9256be2" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_01a17b7b-6ccf-74ad-9924-a0a5ba906280" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_01a17b7d-7bbf-72b0-b559-6c432c115ea4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-7af9-bd44-3dd4d9256be2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_01a17b7d-7bbf-72b0-b559-6c432c115ea4" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationRestrictedStockActivityDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#EquitybasedCompensationRestrictedStockActivityDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationRestrictedStockActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ee-7ae1-a4cb-2715352f845d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ee-7785-8ad9-2ac93f14d8be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ee-7ae1-a4cb-2715352f845d" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ee-7785-8ad9-2ac93f14d8be" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019fed21-32ee-76a7-a19b-bba675b1a261" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ee-7785-8ad9-2ac93f14d8be" xlink:to="loc_us-gaap_AwardTypeAxis_019fed21-32ee-76a7-a19b-bba675b1a261" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ee-76a7-a19b-bba675b1a261_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019fed21-32ee-76a7-a19b-bba675b1a261" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ee-76a7-a19b-bba675b1a261_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ee-7a84-a24a-fecb1bc9b283" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019fed21-32ee-76a7-a19b-bba675b1a261" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ee-7a84-a24a-fecb1bc9b283" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019fed21-32ee-70c8-88e4-7d95150d05d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ee-7a84-a24a-fecb1bc9b283" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019fed21-32ee-70c8-88e4-7d95150d05d4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PerformanceBasedRestrictedStockUnitsMember_019fed21-32ee-77d7-a40e-ef69a151bd99" xlink:href="zi-20260930.xsd#zi_PerformanceBasedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ee-7a84-a24a-fecb1bc9b283" xlink:to="loc_zi_PerformanceBasedRestrictedStockUnitsMember_019fed21-32ee-77d7-a40e-ef69a151bd99" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PerformanceFactorMember_019fed21-32ee-78d8-a4fb-7f39991dd88f" xlink:href="zi-20260930.xsd#zi_PerformanceFactorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ee-7a84-a24a-fecb1bc9b283" xlink:to="loc_zi_PerformanceFactorMember_019fed21-32ee-78d8-a4fb-7f39991dd88f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fed21-32ee-79b0-ae3f-f18acdd1b00d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ee-7ae1-a4cb-2715352f845d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fed21-32ee-79b0-ae3f-f18acdd1b00d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019fed21-32ee-76f3-aca6-65ae2e7ffe30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fed21-32ee-79b0-ae3f-f18acdd1b00d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019fed21-32ee-76f3-aca6-65ae2e7ffe30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019fed21-32ee-7d5a-867c-7eec66549e30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fed21-32ee-79b0-ae3f-f18acdd1b00d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019fed21-32ee-7d5a-867c-7eec66549e30" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionsByPerformanceFactor_019fed21-32ee-7464-a4fb-90139b926987" xlink:href="zi-20260930.xsd#zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionsByPerformanceFactor"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fed21-32ee-79b0-ae3f-f18acdd1b00d" xlink:to="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionsByPerformanceFactor_019fed21-32ee-7464-a4fb-90139b926987" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019fed21-32ee-761a-bba4-93a6dbce5122" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fed21-32ee-79b0-ae3f-f18acdd1b00d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019fed21-32ee-761a-bba4-93a6dbce5122" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019fed21-32ee-7788-bc1c-afb08d298587" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fed21-32ee-79b0-ae3f-f18acdd1b00d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019fed21-32ee-7788-bc1c-afb08d298587" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019fed21-32ee-7db4-afd2-48f25793a8e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fed21-32ee-7f82-890b-00da90697532" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ee-7ae1-a4cb-2715352f845d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fed21-32ee-7f82-890b-00da90697532" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019fed21-32ee-7409-8242-e09179a61cd5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fed21-32ee-7f82-890b-00da90697532" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019fed21-32ee-7409-8242-e09179a61cd5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019fed21-32ee-7ce7-9b0b-a2d2a9baf753" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fed21-32ee-7f82-890b-00da90697532" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019fed21-32ee-7ce7-9b0b-a2d2a9baf753" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionsByPerformanceFactorWeightedAverageGrantDateFairValue_019fed21-32ee-7586-83b7-369ea5bac92f" xlink:href="zi-20260930.xsd#zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionsByPerformanceFactorWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fed21-32ee-7f82-890b-00da90697532" xlink:to="loc_zi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionsByPerformanceFactorWeightedAverageGrantDateFairValue_019fed21-32ee-7586-83b7-369ea5bac92f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019fed21-32ee-7197-bfaf-99c4a4c19b1e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fed21-32ee-7f82-890b-00da90697532" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019fed21-32ee-7197-bfaf-99c4a4c19b1e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019fed21-32ee-7e31-b574-990049ecb30a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fed21-32ee-7f82-890b-00da90697532" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019fed21-32ee-7e31-b574-990049ecb30a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019fed21-32ee-7a94-88f9-c7cd533edef6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationEmployeeStockPurchasePlanDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#EquitybasedCompensationEmployeeStockPurchasePlanDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationEmployeeStockPurchasePlanDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-71f8-8740-af917f535aa3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ef-70e1-8328-609cc0041ca5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-71f8-8740-af917f535aa3" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ef-70e1-8328-609cc0041ca5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019fed21-32ef-7953-8e45-7d1c404467c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ef-70e1-8328-609cc0041ca5" xlink:to="loc_us-gaap_PlanNameAxis_019fed21-32ef-7953-8e45-7d1c404467c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019fed21-32ef-7953-8e45-7d1c404467c1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019fed21-32ef-7953-8e45-7d1c404467c1" xlink:to="loc_us-gaap_PlanNameDomain_019fed21-32ef-7953-8e45-7d1c404467c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019fed21-32ef-7288-a7c8-d582b186a43a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019fed21-32ef-7953-8e45-7d1c404467c1" xlink:to="loc_us-gaap_PlanNameDomain_019fed21-32ef-7288-a7c8-d582b186a43a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_EmployeeStockPurchasePlanMember_019fed21-32ef-70ed-9245-2287e965bce9" xlink:href="zi-20260930.xsd#zi_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019fed21-32ef-7288-a7c8-d582b186a43a" xlink:to="loc_zi_EmployeeStockPurchasePlanMember_019fed21-32ef-70ed-9245-2287e965bce9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_01a17ef1-8922-7b87-b40a-23c98028730a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ef-70e1-8328-609cc0041ca5" xlink:to="loc_srt_RangeAxis_01a17ef1-8922-7b87-b40a-23c98028730a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_01a17ef1-8922-7b87-b40a-23c98028730a_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_01a17ef1-8922-7b87-b40a-23c98028730a" xlink:to="loc_srt_RangeMember_01a17ef1-8922-7b87-b40a-23c98028730a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_01a17ef1-8922-76c6-9ba7-4d6bb33cba96" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_01a17ef1-8922-7b87-b40a-23c98028730a" xlink:to="loc_srt_RangeMember_01a17ef1-8922-76c6-9ba7-4d6bb33cba96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_01a17ef1-bfe7-7bb6-bf88-fc33bcca2ba5" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_01a17ef1-8922-76c6-9ba7-4d6bb33cba96" xlink:to="loc_srt_MinimumMember_01a17ef1-bfe7-7bb6-bf88-fc33bcca2ba5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_01a17ef2-7397-7d06-9b09-1ac83ee48d55" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_01a17ef1-8922-76c6-9ba7-4d6bb33cba96" xlink:to="loc_srt_MaximumMember_01a17ef2-7397-7d06-9b09-1ac83ee48d55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_01a17efa-8192-7c7b-bfc4-1ea08cbb8647" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-71f8-8740-af917f535aa3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_01a17efa-8192-7c7b-bfc4-1ea08cbb8647" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_019fed21-32ef-7ecd-b37e-d7ebd96c8bad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-71f8-8740-af917f535aa3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_019fed21-32ef-7ecd-b37e-d7ebd96c8bad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019fed21-32ef-78d6-8f2c-de8954a630d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-71f8-8740-af917f535aa3" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019fed21-32ef-78d6-8f2c-de8954a630d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_01a17efc-30e3-7bc0-bb17-e7f243368f62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-71f8-8740-af917f535aa3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_01a17efc-30e3-7bc0-bb17-e7f243368f62" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_01a17efc-7158-72e3-b81e-eabee47919b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-71f8-8740-af917f535aa3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_01a17efc-7158-72e3-b81e-eabee47919b8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019fed21-32ef-7d0b-951e-bc404e42783b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-71f8-8740-af917f535aa3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019fed21-32ef-7d0b-951e-bc404e42783b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019fed21-32ef-76c5-bc52-e2cb5336ae32" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-71f8-8740-af917f535aa3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019fed21-32ef-76c5-bc52-e2cb5336ae32" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/EquitybasedCompensationUnamortizedEquitybasedCompensationCostsDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#EquitybasedCompensationUnamortizedEquitybasedCompensationCostsDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/EquitybasedCompensationUnamortizedEquitybasedCompensationCostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-79c9-8b7c-12fde91dc9c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ef-7866-9b43-de740114461b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-79c9-8b7c-12fde91dc9c3" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ef-7866-9b43-de740114461b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019fed21-32ef-7429-8c71-3857a808d360" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ef-7866-9b43-de740114461b" xlink:to="loc_us-gaap_AwardTypeAxis_019fed21-32ef-7429-8c71-3857a808d360" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ef-7429-8c71-3857a808d360_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019fed21-32ef-7429-8c71-3857a808d360" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ef-7429-8c71-3857a808d360_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ef-7062-820b-ad6f2f24e4ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019fed21-32ef-7429-8c71-3857a808d360" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ef-7062-820b-ad6f2f24e4ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019fed21-32ef-7271-9024-9607e4e0b03d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ef-7062-820b-ad6f2f24e4ed" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019fed21-32ef-7271-9024-9607e4e0b03d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PhantomUnitsMember_019fed21-32ef-7d26-bc16-b0effdf22e31" xlink:href="zi-20260930.xsd#zi_PhantomUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ef-7062-820b-ad6f2f24e4ed" xlink:to="loc_zi_PhantomUnitsMember_019fed21-32ef-7d26-bc16-b0effdf22e31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_CEOPremiumPricedPerformanceOptionMember_019fed21-32ef-74d6-ac3d-c67d9ddb5dd6" xlink:href="zi-20260930.xsd#zi_CEOPremiumPricedPerformanceOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fed21-32ef-7062-820b-ad6f2f24e4ed" xlink:to="loc_zi_CEOPremiumPricedPerformanceOptionMember_019fed21-32ef-74d6-ac3d-c67d9ddb5dd6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_01a17b83-76fd-7b3a-8647-e89a49aa7183" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fed21-32ef-7866-9b43-de740114461b" xlink:to="loc_us-gaap_PlanNameAxis_01a17b83-76fd-7b3a-8647-e89a49aa7183" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_01a17b83-76fd-7b3a-8647-e89a49aa7183_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_01a17b83-76fd-7b3a-8647-e89a49aa7183" xlink:to="loc_us-gaap_PlanNameDomain_01a17b83-76fd-7b3a-8647-e89a49aa7183_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_01a17b83-76fd-7436-a761-dfeea8674eee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_01a17b83-76fd-7b3a-8647-e89a49aa7183" xlink:to="loc_us-gaap_PlanNameDomain_01a17b83-76fd-7436-a761-dfeea8674eee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_EmployeeStockPurchasePlanMember_01a17b83-76fd-7d73-8afd-e798f3e78f89" xlink:href="zi-20260930.xsd#zi_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_01a17b83-76fd-7436-a761-dfeea8674eee" xlink:to="loc_zi_EmployeeStockPurchasePlanMember_01a17b83-76fd-7d73-8afd-e798f3e78f89" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019fed21-32ef-76c6-aa5e-a1f04e475d57" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-79c9-8b7c-12fde91dc9c3" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019fed21-32ef-76c6-aa5e-a1f04e475d57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019fed21-32ef-7291-b5d1-1076e707a136" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-79c9-8b7c-12fde91dc9c3" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019fed21-32ef-7291-b5d1-1076e707a136" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019fed21-32ef-73fb-9fab-8efb30af0f8e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fed21-32ef-79c9-8b7c-12fde91dc9c3" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019fed21-32ef-73fb-9fab-8efb30af0f8e" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/SegmentandGeographicDataNarrativeDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#SegmentandGeographicDataNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/SegmentandGeographicDataNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-32ef-77fb-a1c1-871412f0850d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-32ef-700a-a712-bd3dbf269107" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-32ef-77fb-a1c1-871412f0850d" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-32ef-700a-a712-bd3dbf269107" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019fed21-32ef-7bb3-bd8a-ced04d5dd644" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-32ef-700a-a712-bd3dbf269107" xlink:to="loc_srt_StatementGeographicalAxis_019fed21-32ef-7bb3-bd8a-ced04d5dd644" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019fed21-32ef-7bb3-bd8a-ced04d5dd644_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019fed21-32ef-7bb3-bd8a-ced04d5dd644" xlink:to="loc_srt_SegmentGeographicalDomain_019fed21-32ef-7bb3-bd8a-ced04d5dd644_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019fed21-32ef-7a65-a262-0af4601ceae8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019fed21-32ef-7bb3-bd8a-ced04d5dd644" xlink:to="loc_srt_SegmentGeographicalDomain_019fed21-32ef-7a65-a262-0af4601ceae8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019fed21-32ef-7f58-a30c-3ee422614ec7" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019fed21-32ef-7a65-a262-0af4601ceae8" xlink:to="loc_country_US_019fed21-32ef-7f58-a30c-3ee422614ec7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_019fed21-32ef-7f34-a5a4-5388e421cc52" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019fed21-32ef-7a65-a262-0af4601ceae8" xlink:to="loc_us-gaap_NonUsMember_019fed21-32ef-7f34-a5a4-5388e421cc52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019fed21-32ef-7899-a7cc-62f9b798646f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-32ef-700a-a712-bd3dbf269107" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019fed21-32ef-7899-a7cc-62f9b798646f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019fed21-32ef-7899-a7cc-62f9b798646f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019fed21-32ef-7899-a7cc-62f9b798646f" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019fed21-32ef-7899-a7cc-62f9b798646f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019fed21-32ef-7170-8dcd-12b33b0b33a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019fed21-32ef-7899-a7cc-62f9b798646f" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019fed21-32ef-7170-8dcd-12b33b0b33a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsTotalMember_019fed21-32ef-79ef-b3c2-1258b63e70a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsTotalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019fed21-32ef-7170-8dcd-12b33b0b33a0" xlink:to="loc_us-gaap_AssetsTotalMember_019fed21-32ef-79ef-b3c2-1258b63e70a7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_019fed21-32ef-7ca9-a9ad-843f1bf6d4e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019fed21-32ef-7170-8dcd-12b33b0b33a0" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_019fed21-32ef-7ca9-a9ad-843f1bf6d4e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019fed21-32ef-710b-a92b-c2a890fcd4e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-32ef-700a-a712-bd3dbf269107" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019fed21-32ef-710b-a92b-c2a890fcd4e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019fed21-32ef-710b-a92b-c2a890fcd4e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019fed21-32ef-710b-a92b-c2a890fcd4e4" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019fed21-32ef-710b-a92b-c2a890fcd4e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019fed21-32ef-7514-930f-9c4f90cf8431" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019fed21-32ef-710b-a92b-c2a890fcd4e4" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019fed21-32ef-7514-930f-9c4f90cf8431" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicConcentrationRiskMember_019fed21-32ef-7915-add0-990d79652144" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeographicConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019fed21-32ef-7514-930f-9c4f90cf8431" xlink:to="loc_us-gaap_GeographicConcentrationRiskMember_019fed21-32ef-7915-add0-990d79652144" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_019fed21-32ef-7ca9-b4f6-82a20a256d85" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-32ef-77fb-a1c1-871412f0850d" xlink:to="loc_us-gaap_NumberOfOperatingSegments_019fed21-32ef-7ca9-b4f6-82a20a256d85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_019fed21-32ef-7848-9c48-5b8aaba7aeac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-32ef-77fb-a1c1-871412f0850d" xlink:to="loc_us-gaap_NumberOfReportableSegments_019fed21-32ef-7848-9c48-5b8aaba7aeac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncurrentAssets_019fed21-32ef-786f-b39d-2434eb0ec751" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-32ef-77fb-a1c1-871412f0850d" xlink:to="loc_us-gaap_NoncurrentAssets_019fed21-32ef-786f-b39d-2434eb0ec751" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019fed21-32ef-74b9-9e2c-e38f069c02df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-32ef-77fb-a1c1-871412f0850d" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019fed21-32ef-74b9-9e2c-e38f069c02df" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/SegmentandGeographicDataRevenueDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#SegmentandGeographicDataRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/SegmentandGeographicDataRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-32ef-763e-a049-fc50c4a55d1e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-32ef-7510-babf-7e3771c492b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-32ef-763e-a049-fc50c4a55d1e" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-32ef-7510-babf-7e3771c492b2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019fed21-32ef-7f82-a743-b153740ceb24" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019fed21-32ef-7510-babf-7e3771c492b2" xlink:to="loc_srt_StatementGeographicalAxis_019fed21-32ef-7f82-a743-b153740ceb24" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019fed21-32ef-7f82-a743-b153740ceb24_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019fed21-32ef-7f82-a743-b153740ceb24" xlink:to="loc_srt_SegmentGeographicalDomain_019fed21-32ef-7f82-a743-b153740ceb24_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019fed21-32ef-73f4-9f2c-741af2cea2fa" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019fed21-32ef-7f82-a743-b153740ceb24" xlink:to="loc_srt_SegmentGeographicalDomain_019fed21-32ef-73f4-9f2c-741af2cea2fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019fed21-32ef-74b3-9ccd-982d78bd5e2a" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019fed21-32ef-73f4-9f2c-741af2cea2fa" xlink:to="loc_country_US_019fed21-32ef-74b3-9ccd-982d78bd5e2a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_019fed21-32ef-773d-8c68-aa7c57011db1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019fed21-32ef-73f4-9f2c-741af2cea2fa" xlink:to="loc_us-gaap_NonUsMember_019fed21-32ef-773d-8c68-aa7c57011db1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fed21-32ef-796e-aa40-6e1dcb7691f6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019fed21-32ef-763e-a049-fc50c4a55d1e" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fed21-32ef-796e-aa40-6e1dcb7691f6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.zoominfo.com/role/SegmentandGeographicDataSegmentInformationDetails" xlink:type="simple" xlink:href="zi-20260930.xsd#SegmentandGeographicDataSegmentInformationDetails"/>
  <link:definitionLink xlink:role="http://www.zoominfo.com/role/SegmentandGeographicDataSegmentInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019fed21-32ef-7201-b532-a46d8704b68b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fed21-32ef-7f8a-9278-24da508bc7af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fed21-32ef-7201-b532-a46d8704b68b" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fed21-32ef-7f8a-9278-24da508bc7af" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019fed21-32ef-7d55-899e-968161486ee4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fed21-32ef-7f8a-9278-24da508bc7af" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019fed21-32ef-7d55-899e-968161486ee4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fed21-32ef-7d55-899e-968161486ee4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019fed21-32ef-7d55-899e-968161486ee4" xlink:to="loc_us-gaap_SegmentDomain_019fed21-32ef-7d55-899e-968161486ee4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fed21-32ef-7d77-83e1-b26e80cb1ccd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019fed21-32ef-7d55-899e-968161486ee4" xlink:to="loc_us-gaap_SegmentDomain_019fed21-32ef-7d77-83e1-b26e80cb1ccd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_ReportableSegmentMember_019fed21-32ef-7f4d-a5b0-e07bef6e026c" xlink:href="zi-20260930.xsd#zi_ReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fed21-32ef-7d77-83e1-b26e80cb1ccd" xlink:to="loc_zi_ReportableSegmentMember_019fed21-32ef-7f4d-a5b0-e07bef6e026c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fed21-32ef-7fe9-bcb2-8f9f405bef69" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fed21-32ef-7201-b532-a46d8704b68b" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fed21-32ef-7fe9-bcb2-8f9f405bef69" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationAdditionalInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fed21-32ef-7201-b532-a46d8704b68b" xlink:to="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LaborAndRelatedExpense_019fed21-32ef-741a-b3f8-ee067c6e07e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LaborAndRelatedExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_us-gaap_LaborAndRelatedExpense_019fed21-32ef-741a-b3f8-ee067c6e07e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_PayrollTaxAndBenefitsExpense_019fed21-32ef-7155-8426-a8267c9b9b82" xlink:href="zi-20260930.xsd#zi_PayrollTaxAndBenefitsExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_zi_PayrollTaxAndBenefitsExpense_019fed21-32ef-7155-8426-a8267c9b9b82" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_TechnologyExpense_019fed21-32ef-7ac2-84b0-ea80ab4df95f" xlink:href="zi-20260930.xsd#zi_TechnologyExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_zi_TechnologyExpense_019fed21-32ef-7ac2-84b0-ea80ab4df95f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketingExpense_019fed21-32ef-7e0a-89da-621c9ad04a98" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_us-gaap_MarketingExpense_019fed21-32ef-7e0a-89da-621c9ad04a98" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_FacilitiesExpense_019fed21-32ef-7feb-a7ce-b48919d042a4" xlink:href="zi-20260930.xsd#zi_FacilitiesExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_zi_FacilitiesExpense_019fed21-32ef-7feb-a7ce-b48919d042a4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForLoanLossesExpensed_019fed21-32ef-7594-9e53-88d6409a4f7d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProvisionForLoanLossesExpensed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_us-gaap_ProvisionForLoanLossesExpensed_019fed21-32ef-7594-9e53-88d6409a4f7d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_HostingAndInfrastructureExpense_019fed21-32ef-7daf-a343-f18df9691012" xlink:href="zi-20260930.xsd#zi_HostingAndInfrastructureExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_zi_HostingAndInfrastructureExpense_019fed21-32ef-7daf-a343-f18df9691012" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_019fed21-32ef-7382-b504-70ab43df7621" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_019fed21-32ef-7382-b504-70ab43df7621" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDepreciationAndAmortization_019fed21-32ef-7a48-8ecf-e51dc932a2e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_us-gaap_OtherDepreciationAndAmortization_019fed21-32ef-7a48-8ecf-e51dc932a2e5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_019fed21-32ef-7c6e-9d43-1c3d34937c64" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_019fed21-32ef-7c6e-9d43-1c3d34937c64" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019fed21-32ef-756c-9a42-a0c906d3171c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019fed21-32ef-756c-9a42-a0c906d3171c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019fed21-32ef-7fef-92a6-df54d62f2ab5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019fed21-32ef-7fef-92a6-df54d62f2ab5" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019fed21-32ef-7441-ac51-13c5522e9eb1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019fed21-32ef-7441-ac51-13c5522e9eb1" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019fed21-32ef-73fb-9745-cdb6a908d76a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_019fed21-32ef-7299-ad16-d6c55e13d2e8" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019fed21-32ef-73fb-9745-cdb6a908d76a" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019fed21-32ef-7654-b9d1-186f5ae437c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fed21-32ef-7201-b532-a46d8704b68b" xlink:to="loc_us-gaap_NetIncomeLoss_019fed21-32ef-7654-b9d1-186f5ae437c3" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_zi_JamesRothMember_01a17b93-8fce-76e6-b47a-73f7cadf0781" xlink:href="zi-20260930.xsd#zi_JamesRothMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_zi_JamesRothMember_01a17b93-8fce-76e6-b47a-73f7cadf0781" xlink:type="arc" order="2"/>
  </link:definitionLink>
</link:linkbase>
