folly

 
Pronunciation: /ˈfɒli/

noun (plural follies)

  • 1 [mass noun] lack of good sense; foolishness: an act of sheer folly
  • [count noun] a foolish act, idea, or practice: the follies of youth
  • 2a costly ornamental building with no practical purpose, especially a tower or mock-Gothic ruin built in a large garden or park.
  • 3 (Follies) a theatrical revue with glamorous female performers: [in names]: the Ziegfeld Follies

Origin:

Middle English: from Old French folie 'madness', in modern French also 'delight, favourite dwelling' (compare with folly (sense 2)), from fol 'fool, foolish'