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folly

American  
[fol-ee] / ˈfɒl i /

noun

  • follies
    plural
  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.

    Synonyms:
    lunacy, madness, injudiciousness, indiscretion, foolishness, mistake, rashness, imprudence
  3. a costly and foolish undertaking; unwise investment or expenditure.

  4. Architecture. a whimsical or extravagant structure built to serve as a conversation piece, lend interest to a view, commemorate a person or event, etc.: found especially in England in the 18th century.

  5. follies, a theatrical revue.

  6. Obsolete. wickedness; wantonness.


folly British  
/ ˈfɒlɪ /

noun

  1. the state or quality of being foolish; stupidity; rashness

  2. a foolish action, mistake, idea, etc

  3. a building in the form of a castle, temple, etc, built to satisfy a fancy or conceit, often of an eccentric kind

  4. (plural) theatre an elaborately costumed revue

  5. archaic

    1. evil; wickedness

    2. lewdness; wantonness

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Usage

What does folly mean? A folly is a foolish action. Follies can refer to various unwise practices, buildings with a purely ornamental purpose, or cabaret-style theatrical revues featuring lots of beautiful, dancing women.

Other Word Forms

Derived Forms

Inflected Forms

Nouns

Etymology

Origin of folly

First recorded in 1175–1225; Middle English folie, from Old French, derivative of fol, fou “foolish, mad”; equivalent to fool 1 + -y 3 ( def. )

Explanation

Folly is a noun that means "foolish or crazy behavior." It would be folly to spend all night playing video games when you have a difficult exam the next day. Folly comes from the Old French word folie meaning "madness, stupidity." It can describe the silly or nonsensical things you do, like the folly of trying to rush across town in the middle of a snowstorm. Or it can describe the trait that makes people act that way: the folly of an inexperienced driver who doesn't know you can't speed on snow-covered roads. Can you see the word fool in folly? Not a coincidence.

Keep Reading on Vocabulary.com

Vocabulary lists containing folly

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

"Prolonging this parasitic relationship by trying to squeeze the last few drops of expensive oil out of the North Sea is sheer folly," Hopkinson said.

From BBC Aug. 4, 2026

When the entire forest appeared to be storming his stronghold, Macbeth realized his folly too late.

From The Wall Street Journal Jul. 30, 2026

Gold is the color of false idolatry, the material of gratuitous wealth, a hallmark of authoritarian style, and a metaphor for the folly of prioritizing personal enrichment and glory over everything else.

From Slate Jun. 11, 2026

The folly of youth and the harsh realities of old age make uncomfortable bedfellows.

From MarketWatch May 7, 2026

If he loved you, he would come and carry you off at swordpoint, as Rhaegar carried off his northern girl, the girl in her insisted, but the queen knew that was folly.

From "A Dance with Dragons" by George R. R. Martin

In an essay for this year's Proms programme, he admitted that some of the genre's "excesses and follies can seem silly" to a modern eye, while insisting the genre shouldn't be written off.

From BBC Apr. 20, 2026

People forget about past follies, either by choice and/or because they’re distracted by the next shiny thing.

From MarketWatch Feb. 6, 2026

More aggressive fine print restrains other follies like the bond portfolio mismatches that undid California-based Silicon Valley Bank two years ago, says Davide Oneglia, director of European and global macro at TS Lombard.

From Barron's Oct. 25, 2025

Amid follies aplenty, gold has doubled in the past two years.

From The Wall Street Journal Oct. 18, 2025

It was true that he had never fully lost himself in another person to such an extent as to forget himself; he had never undergone the follies of love for another person.

From "Siddhartha" by Hermann Hesse

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