lu·​na·​cy | \ ˈlü-nə-sē How to pronounce lunacy (audio) \
plural lunacies

Definition of lunacy

1 dated
b : intermittent insanity once believed to be related to phases of the moon
2 : wild foolishness : extravagant folly
3 : a foolish act

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Examples of lunacy in a Sentence

Quitting her job was lunacy. His idea was considered total lunacy.
Recent Examples on the Web As clocks crept toward midnight Friday in downtown San Diego — 3 a.m. on the East Coast, lunchtime in Mumbai and who-knows-what on the moon — the Padres and Dodgers refused to loosen their grip on lunacy. San Diego Union-Tribune, "Column: Wild Padres-Dodgers opener sign of budding rivalry," 17 Apr. 2021 In a year when entertainment felt less like a distraction and more like a survival tool, television stepped in to deliver us from boredom, stress and cabin-fever lunacy. San Diego Union-Tribune, "Column: The best TV of 2020 offered escape and perspective," 25 Dec. 2020 And yet this 2017 piece of lunacy is kind of an amazing B-movie, especially the final act that includes a couple of the guys from The Raid movies fighting aliens and other dudes. Jordan Crucchiola, Vulture, "The 50 Best Action Movies on Netflix Right Now," 15 Jan. 2021 That this idea has to be debated or defended is lunacy. Rodney Stevens, WSJ, "If You Must Talk About Race, Be Gracious," 28 Dec. 2020 This is lunacy on both sides, all around, no answers, no one truly knowing what to do besides march forward until the NCAA or the Big East decides enough is enough. Mike Anthony,, "Mike Anthony: Geno Auriemma and UConn about to cross a finish line by entering the starting gate to 2020-21 season," 12 Dec. 2020 Check out Johnson’s latest eco-lunacy for part of the reason why. Andrew Stuttaford, National Review, "The Capital Letter: Week of November 16," 21 Nov. 2020 But the lunacy of the various components — the goofy bill, the indifferent insurer, the self-serving reversal — highlight how far our healthcare system is out of whack. Los Angeles Times, "Column: A $336 Band-Aid for a cut finger? Our healthcare system is nuts," 8 Dec. 2020 To outside observers, Indiana football coach Tom Allen’s style of coaching is enthusiasm bordering on lunacy. Laine Higgins, WSJ, "Indiana Is Finally Proving to Be More Than a Basketball School," 17 Nov. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'lunacy.' 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 lunacy

1541, in the meaning defined at sense 1a

History and Etymology for lunacy


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Statistics for lunacy

Last Updated

29 Apr 2021

Cite this Entry

“Lunacy.” Dictionary, Merriam-Webster, Accessed 7 May. 2021.

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More Definitions for lunacy


lu·​na·​cy | \ ˈlü-nə-sē How to pronounce lunacy (audio) \
plural lunacies

Medical Definition of lunacy

: mental illness also : intermittent mental illness once believed to be related to phases of the moon


lu·​na·​cy | \ ˈlü-nə-sē How to pronounce lunacy (audio) \

Legal Definition of lunacy

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Comments on lunacy

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