X0609 4 2026-06-04 0001861795 Definitive Healthcare Corp. DH 0001645772 Hamood Samuel A false C/O DEFINITIVE HEALTHCARE CORP. 492 OLD CONNECTICUT PATH, SUITE 401 FRAMINGHAM MA 01701 true false false false false Class A Common Stock 2026-06-04 4 A false 189190 0 A 289396 D Class A Common Stock 51582 I By AMHAM DH LLC Represents restricted stock units ("RSUs"), each representing a contingent right to receive one share of the Issuer's Class A Common Stock, par value $0.001, vesting on the earlier of June 4, 2027 or the date of the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service through the applicable vesting date. /s/ Jonathan Paris, Attorney-in-Fact 2026-06-08