lunatic
Americannoun
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(no longer in technical use; now considered offensive) an insane person.
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a person whose actions and manner are marked by extreme eccentricity or recklessness.
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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
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(no longer in technical use; now considered offensive) insane.
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characteristic or suggestive of lunacy; wildly or recklessly foolish.
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Older Use. designated for or used by the insane.
a lunatic asylum.
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gaily or lightheartedly mad, frivolous, eccentric, etc..
She has a lunatic charm that is quite engaging.
adjective
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an archaic word for insane
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foolish; eccentric; crazy
noun
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.
Vocabulary lists containing lunatic
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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.
"The city is going to bear the scars of this lunatic for a really long time."
From Barron's • May 15, 2026
Mr. Gittlitz writes with the lunatic panache of a utopian manifesto or 2000s sports blog.
From The Wall Street Journal • Mar. 27, 2026
That is a deliberate choice, says Tracy, because Teddy is not -- or at least not just -- a lunatic.
From Barron's • Mar. 1, 2026
“It’s easy to quickly and thoughtless write this off as the manifesto of a lunatic, in order to avoid facing some of the uncomfortable problems it identifies,” Mangione wrote.
From Los Angeles Times • Dec. 11, 2024
“But it’s infected,” I continued, trying to provide a little more information without sounding like a lunatic.
From "Summer of the Mariposas" by Guadalupe García McCall
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
