A climax is usually taken to mean "The highest point of anything reached by gradual ascent; the culmination, height, acme, apex". In language, climax is properly a rise in emotion, especially tension. The figure of speech named climax is defined as: "1. Rhet. A figure in which a number of propositions or ideas are set forth so as to form a series in which each rises above the preceding in force or effectiveness of expression" (OED). The adjective is climactic.
- (You may like to see also anticlimax for which there is the adjective anticlimactic.)