1. lack of good sense; foolishness: "an act of sheer folly"
▪ a foolish act, idea, or practice: "the follies of youth"
2. a costly ornamental building with no practical purpose, especially a tower or mock-Gothic ruin built in a large garden or park.
3. a theatrical revue with glamorous female performers:"the Ziegfeld Follies"
Word OriginMiddle English: from Old French folie ‘madness’, in modern French also ‘delight, favorite dwelling’ (compare with folly (sense 2)), from fol ‘fool, foolish’.