climax has 6 distinct synonyms spread across 4 of its 6 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
the highest point of anything conceived of as growing or developing or unfolding
“the climax of the artist's career”
the decisive moment in a novel or play
“the deathbed scene is the climax of the play”
Synonyms, antonyms and the broader and narrower relations for climax come from Princeton University’s WordNet. Full sources and licences.
the moment of most intense pleasure in sexual intercourse
arrangement of clauses in ascending order of forcefulness