"the addition of a particular which suddenly lowers the effect," 1701, from anti- + climax (n.).

a drop, often sudden and unexpected, from a dignified or important idea or situation to one that is trivial or humorous. Also a sudden descent from something sublime to something ridiculous. In fictio [..]

n. A gradual or sudden decrease in the importance or impressiveness of what is said.

a slackening of tension in a sentence or longer piece of writing wherein the ideas fall off in dignity, or become less important at the close. "The wind sung..., and the sailors swore"

(n) a disappointing decline after a previous rise(n) a change from a serious subject to a disappointing one

Your book is building up to something intense, right? Your two favorite characters are about to kiss. Or the hero is only pages away from slaying the dragon. Or the detective is just steps behind the [..]