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.

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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

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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

• superfolly
  noun

Inflected Forms

Nouns

• follies
  plural

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.

Example Sentences

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

As the cautionary 1945 fable “Animal Farm” memorably shows, George Orwell had some thoughts about the Soviet Union and the terrible folly in politicized moralism.

From Los Angeles Times • May 1, 2026

Yet, “Pretty Lethal” is packed with run-don’t-walk folly that demands to be seen to be believed — if only to throw up your hands and say, “I guess!”

From Salon • Mar. 29, 2026

I told them this was folly, but none of them would listen.

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

Related Words

• absurdity
• craziness
• foolishness
• idiocy
• indiscretion
• lunacy
• madness
• recklessness
• silliness
• stupidity