lu·​na·​tic | \ ˈlü-nə-ˌtik How to pronounce lunatic (audio) \

Definition of lunatic

1 dated
a : affected with a severely disordered state of mind : insane
b : designed for the care of mentally ill people a lunatic asylum
2 : wildly foolish a lunatic idea lunatic behavior

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Other Words from lunatic

lunatic noun

Synonyms & Antonyms for lunatic



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Examples of lunatic in a Sentence

He hatched a lunatic plot to overthrow the government. another of his lunatic ideas
Recent Examples on the Web Of course, he was most bemused about the attempt to find evidence of bamboo fibers on the ballots, part of a lunatic right-wing conspiracy theory involving ballots sent from Asia. Bill Goodykoontz, The Arizona Republic, 7 May 2021 It’s another to connect that to a belief in something that appears obviously lunatic like QAnon. David Marchesephoto Illustration By Bráulio Amado, New York Times, 9 Apr. 2021 In fact, all of the outfits are stellar, from Lawrence as some kind of camp voodoo doll to Ellie Diamond, who looks like a lunatic Snow White. Brian Moylan, Vulture, 12 Mar. 2021 Bruno fulfills his end of the deal, but Guy, the other man, never took the pact seriously and refuses to cooperate, sending Bruno into a downward spiral of lunatic frenzy. Terry Teachout, WSJ, 24 Feb. 2021 Few people would stand for a system in which users can be punished for the lunatic interpretations of their followers. Gilad Edelman, Wired, 8 Jan. 2021 Strong absolutely nailed Carone’s appearance, complete with slurred and mispronounced words and lunatic claims and accusations. Bill Goodykoontz, The Arizona Republic, 7 Dec. 2020 Three helicopters hovered, their rotors rattling like a lunatic washing machine. Dave Eggers, The New Yorker, 16 Nov. 2020 A week or so later, after receiving another call from the waitress, Tommy returned to the house and opened the door, which, oddly enough given the lunatic views of its inhabitant on the subject of privacy, was unlocked. Matthew Walther, TheWeek, 10 Oct. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'lunatic.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of lunatic

14th century, in the meaning defined at sense 1a

History and Etymology for lunatic

Middle English lunatik, from Anglo-French or Late Latin; Anglo-French lunatic, from Late Latin lunaticus, from Latin luna; from the belief that lunacy fluctuated with the phases of the moon

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Time Traveler for lunatic

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The first known use of lunatic was in the 14th century

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Statistics for lunatic

Last Updated

17 May 2021

Cite this Entry

“Lunatic.” Dictionary, Merriam-Webster, Accessed 19 Jun. 2021.

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More Definitions for lunatic



English Language Learners Definition of lunatic

old-fashioned + sometimes offensive : designed for insane people
: not sane
: wildly foolish


lu·​na·​tic | \ ˈlü-nə-ˌtik How to pronounce lunatic (audio) \

Kids Definition of lunatic

 (Entry 1 of 2)



Kids Definition of lunatic (Entry 2 of 2)

1 : an insane person
2 : a person who behaves very foolishly That lunatic went through a red light.


lu·​na·​tic | \ ˈlü-nə-ˌtik How to pronounce lunatic (audio) \

Medical Definition of lunatic

dated, now offensive : an individual marked by a severely disordered state of mind

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lu·​na·​tic | \ ˈlü-nə-tik \

Legal Definition of lunatic

: an insane person used especially formerly

Other Words from lunatic

lunatic adjective


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