folly

American  

[fol-ee] / ˈfɒl i /

noun

plural

follies

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

• superfolly
  noun

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

Another possibility is The Folly - a three-bedroom, two-bathroom lodge built in the 1800s.

From BBC • Oct. 31, 2025

The license was originally issued under heavy pressure from Rousseff’s government, said Folly.

From Washington Times • May 7, 2023

The whole place was strangely scentless: a spread of neo-brutalism and Faraday Cage Folly architecture, sterile sculptures studded with hostile textures, quasi-public outbuildings like amphitheaters and gazebos that were functionally useless and inaccessible.

From Slate • Aug. 27, 2022

Tim Weiner’s most recent book is “The Folly and the Glory: America, Russia, and Political Warfare 1945-2020.”

From Washington Post • Mar. 25, 2022

We rode down Route 127 to Folly Cove, passing a mile of granite curbing and houses built with granite blocks.

From "The Line Tender" by Kate Allen

Related Words

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