Foolishness that results from a lack of foresight or lack of practicality. / Thoughtless action resulting in tragic consequence. / (architecture) A fanciful building built for purely ornamental reasons.

(obsolete) Full of folly; foolish.

plural of folly / (uncountable) A lavishly-produced theatrical revue characterized by major stars, huge casts, and opulent costumes and scenery.

(numismatics) A large bronze coin minted during the Roman Empire.

A tower built as an architectural folly, i.e. for ornamental rather than practical reasons.

plural of folly tower

An unofficial nickname for the state of Alaska in the United States of America.

Foolish people repeatedly do foolish things.