folly
UK: ˈfɒli | US: ˈfɑːli
n. a foolish act, idea, or practice; lack of good sense
n. (archaic) a costly ornamental building with no practical purpose
The word "folly" originates from Old French folie (madness, foolishness), derived from fol (fool, from Latin follis, meaning "bellows" or "windbag," later metaphorically "empty-headed person"). The suffix -ie (later anglicized to -y) formed abstract nouns. Over time, "folly" evolved to denote both foolish behavior and extravagant, impractical structures (e.g., garden follies), reflecting the whimsicality of poor judgment.
Investing all his savings in a scam was sheer folly.
The ruined tower on the estate was built as a folly in the 18th century.
Her decision to quit her job without a plan seemed like folly.
The king’s folly led to the kingdom’s downfall.
Critics dismissed the project as an expensive folly.