Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

  

lunacy

 
/ˈlu·nə·si/ n [U]

Definition

extreme foolishness or mental illness: It would be lunacy to try and climb the mountain in this weather.
(Definition of lunacy n from the Cambridge Academic Content Dictionary © Cambridge University Press)

“lunacy” in other dictionaries

Word of the Day

everything under the sun

everything that exists or is possible

Word of the Day

Blog

Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More