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lunatic

American  
[loo-nuh-tik] / ˈlu nə tɪk /

noun

  1. (no longer in technical use; now considered offensive) an insane person.

  2. a person whose actions and manner are marked by extreme eccentricity or recklessness.

  3. a person legally declared to be of unsound mind and who therefore is not held capable or responsible before the law: a former legal term.


adjective

  1. (no longer in technical use; now considered offensive) insane.

  2. characteristic or suggestive of lunacy; wildly or recklessly foolish.

  3. Older Use. designated for or used by the insane.

    a lunatic asylum.

  4. gaily or lightheartedly mad, frivolous, eccentric, etc..

    She has a lunatic charm that is quite engaging.

lunatic British  
/ ˈluːnətɪk /

adjective

  1. an archaic word for insane

  2. foolish; eccentric; crazy

"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

noun

  1. a person who is insane

"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

Other Word Forms

Etymology

Origin of lunatic

1250–1300; Middle English lunatik, from Old French lunatique, from Late Latin lūnāticus “moonstruck.” See Luna, -tic ( def. )

Explanation

A lunatic is someone who is either clinically insane or just acting really crazy. Someone driving too fast and zigging in and out of traffic is driving like a lunatic. The root of this word is luna, which means moon. That's because lunatic originally meant someone who went crazy with every phase of the moon, kind of like a werewolf. Most people these days don't believe in moon-caused insanity, but we still talk about lunatics, sometimes meaning clinically insane people. More often this is a slang term, used mainly in exaggerations, for anyone who seems wild and out of control.

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Vocabulary lists containing lunatic

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.

In a Somerset town a small group of volunteers are slowly and sensitively revealing the stories of those who lived at the Somerset and Bath Pauper Lunatic Asylum.

From BBC • Feb. 26, 2023

Carl Hoffman is the author of five books, including “Savage Harvest,” “The Lunatic Express” and “Liar’s Circus.”

From Washington Post • Feb. 23, 2023

FREETOWN, Sierra Leone — For centuries, they called the foreboding building on a hill above this capital city the Kissy Lunatic Asylum.

From New York Times • Apr. 11, 2022

Tomas Kubinek: Certified Lunatic and Master of the Impossible The vaudeville-style performer mixes theater, magic and circus arts.

From Los Angeles Times • Apr. 19, 2019

“You didn’t tell us where that maniac’s escaped from! What use is that? Lunatic could be coming up the street right now!”

From "Harry Potter And The Prisoner Of Azkaban" by J.K. Rowling