folly

noun

fol·​ly ˈfä-lē 

plural follies

1

: lack of good sense or normal prudence and foresight

his folly in thinking he could not be caught

2

a

: criminally or tragically foolish actions or conduct

"It was folly, pure folly," protested Lingard, "and this poor fellow has paid for it."

—Joseph Conrad

b

obsolete : evil, wickedness

especially : lewd behavior

3

: a foolish act or idea

The prank was a youthful folly.

4

: an excessively costly or unprofitable undertaking

Paying so much for that land was folly, since it was all rocks.

5

: an often extravagant picturesque building erected to suit a fanciful taste

Synonyms of folly

• insanity
• absurdity
• idiocy
• stupidity

Examples of folly in a Sentence

the folly of driving fast on steep, winding roads

his folly in thinking that he would not be noticed

The folly of such an action should be apparent to everyone.

the follies of the modern world

the famous Ziegfeld Follies of the 1920s

Recent Examples on the Web

Republicans also know how unpopular — like, really unpopular — Trump’s Greenland folly has been. —S.e. Cupp, New York Daily News, 22 Jan. 2026

Here the glory is threaded with human folly. —Owen Gleiberman, Variety, 22 Jan. 2026

Reflexively siding with or against law enforcement is folly. —Megan McArdle, Washington Post, 10 Jan. 2026

This is a scrapbook of utopian folly, yes, but also an insider’s look at what was, for a time, the wildest workplace on Earth. —Boris Kachka, The Atlantic, 9 Jan. 2026

Word History

Etymology

Middle English folie, from Anglo-French, from fol fool

First Known Use

13th century, in the meaning defined at sense 1

Rhymes for folly

• colley
• collie
• dolly
• golly
• holly
• jolley
• jolly
• lolly
• mollie
• molly
• ollie
• polly

Kids Definition

folly

noun

fol·​ly ˈfäl-ē 

plural follies

1

: lack of good sense or judgment

2

: foolish behavior

3

: a foolish act or idea