folly

(noun) the trait of acting stupidly or rashly. Synonyms: foolishness, unwiseness.

(noun) a stupid mistake. Synonyms: stupidity, betise, foolishness, imbecility.

(noun) the quality of being rash and foolish. Synonyms: foolishness, craziness, madness. Examples: "Trying to drive through a blizzard is the height of folly." "Adjusting to an insane society is total foolishness."

(noun) foolish or senseless behavior. Synonyms: foolery, tomfoolery, craziness, lunacy, indulgence.