WordNet (r) 3.0 (2006):

sexual climax
    n 1: the moment of most intense pleasure in sexual intercourse
         [syn: orgasm, climax, sexual climax, coming]

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "sexual climax":
   access, act of love, adultery, aphrodisia, apoplexy, ass, attack,
   balling, carnal knowledge, climax, cohabitation, coition, coitus,
   coitus interruptus, commerce, congress, connection, convulsion,
   copula, copulation, coupling, cramp, diddling, eclampsia, epilepsy,
   epitasis, falling sickness, fit, fornication, grip, ictus,
   intercourse, intimacy, lovemaking, making it with,
   marital relations, marriage act, mating, meat, onanism, orgasm,
   ovum, pareunia, paroxysm, procreation, relations, screwing,
   seizure, sex, sex act, sexual commerce, sexual congress,
   sexual intercourse, sexual relations, sexual union, sleeping with,
   spasm, sperm, stroke, throes, venery