Pronunciation: (fol'ē),[key] —n., —pl.-liesfor 2–6. 1. the state or quality of being foolish; lack of understanding or sense.
2. a foolish action, practice, idea, etc.; absurdity: the folly of performing without a rehearsal. 3. a costly and foolish undertaking; unwise investment or expenditure.
4. Archit.a whimsical or extravagant structure built to serve as a conversation piece, lend interest to a view, commemorate a person or event, etc.: found esp. in England in the 18th century.
5. follies,a theatrical revue.
6. Obs.wickedness; wantonness.