The turning point in the action of a drama; in tragedy, it is usually the moment that the tragic protagonist loses the initiative and the momentum and the drama turns from success to failure. In comedy, it is usually the moment that the comic protagonist gains the initiative or a chance occurrence turns the action from misfortune to fortune.
Climax is "the part of a story or play at which a crisis is reached and resolution achieved" (Cuddon 141).
Cudden, J. A. The Penguin Dictionary of Literary Terms and Literary Theory. Fourth Edition. Great Britain, Penguin Group, 1977.