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1. The trait of acting stupidly or rashly
   - foolishness, unwiseness
    
2. A stupid mistake
   - stupidity, bêtise, foolishness, imbecility
    
3. The quality of being rash and foolish
   "trying to drive through a blizzard is the height of folly";
   - foolishness, craziness, madness, nuttiness [informal], insanity
    
4. Foolish or senseless behaviour
   - foolery, tomfoolery, craziness, lunacy, indulgence
    
5. A fanciful building built for purely ornamental reasons

Derived forms: follies

Type of: caper [informal], daftness [informal], error, fault, frolic, gambol, mistake, play, romp, stupidity, trait

Encyclopedia: Folly, Virginia