Yes, climax is a Scrabble word!

Verb

1. End, especially to reach a final or climactic stage

Noun

1. The highest point of anything conceived of as growing or developing or unfolding

2. The decisive moment in a novel or play

3. The moment of most intense pleasure in sexual intercourse

4. The most severe stage of a disease

5. Arrangement of clauses in ascending order of forcefulness