in·​sane | \(ˌ)in-ˈsān \

Definition of insane 

1a(1) : exhibiting a severely disordered state of mind : affected with mental illness

(2) law : affected with insanity (see insanity sense 2) criminally insane

b : unable to think in a clear or sensible way : crazy insane with jealousy not used technically

2 : used by, typical of, or intended for mentally ill people an insane asylum

3 : absurd an insane scheme for making money

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Other Words from insane

insanely adverb
insaneness \(ˌ)in-​ˈsān-​nəs \ noun

Synonyms & Antonyms for insane


balmy, barmy [chiefly British], bats, batty, bedlam, bonkers, brainsick, bughouse [slang], certifiable, crackbrained, cracked, crackers, crackpot, cranky [dialect], crazed, crazy, cuckoo, daffy, daft, demented, deranged, fruity [slang], gaga, haywire, kooky (also kookie), loco [slang], loony (also looney), loony tunes (or looney tunes), lunatic, mad, maniacal (also maniac), mental, meshuga (or meshugge), moonstruck, non compos mentis, nuts, nutty, psycho, psychotic, scatty [chiefly British], screwy, unbalanced, unhinged, unsound, wacko (also whacko), wacky (also whacky), wud [chiefly Scottish]


balanced, compos mentis, sane, sound, uncrazy

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Examples of insane in a Sentence

The murderer was found to be criminally insane. She was insane with jealousy. He had an insane look in his eyes. She likes to drive at insane speeds. He had this insane idea that he could get rich by selling old computers.
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Recent Examples on the Web

Anyway, in the end Strode, her daughter, and her granddaughter force Myers into the basement before revealing two more insane details of the house. Alyssa Fiorentino, House Beautiful, "The Custom Basement In 'Halloween' Is The Best Part Of This Sequel," 23 Oct. 2018 In the October issue The October issue features a review of the Acer Predator 21 X, the most insane laptop ever built. Pcworld Staff, PCWorld, "PCWorld's October Digital Magazine: Acer's Predator X27 gaming monitor," 10 Oct. 2018 The deal was insane, terrible and ridiculous, Trump said. Wael Mahdi, Houston Chronicle, "OPEC seeks last minute compromise as Iran opposes supply boost," 22 June 2018 Referees make bad calls because basketball is impossible to officiate, and fans who love basketball will generally go insane when those calls hurt their team. Andrew Sharp,, "An Inexplicable Calls Stains a Legendary NBA Finals Thriller," 1 June 2018 Since my last visit, traffic in San Francisco has become even more insane, with bike lanes and car-blocking bus stops proliferating, making a drive home like calculating a miniature golf putt. Michael Bauer, San Francisco Chronicle, "Michael Bauer’s trip to Kansas: $17 main courses and homes for $75,000," 15 May 2018 Meghan Markle and Prince Harry's schedule for their first royal tour together in Australia has been insane. Amy Mackelden, Harper's BAZAAR, "Meghan Markle Just Wore the Chicest Emilia Wickstead Dress, & It's Still Available to Shop," 20 Oct. 2018 Out of the box, this PC will hit most spec requirements, which is insane at this price. Alexander George, Popular Mechanics, "How To Get Into the High-Powered World of Gaming PCs," 20 Sep. 2018 Unsurprisingly, Bieber dropped an insane amount of money on the ring. Sarah Spellings, The Cut, "Justin Bieber Dropped $500,000 on Hailey Baldwin’s Engagement Ring," 13 July 2018

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

circa 1550, in the meaning defined at sense 1

History and Etymology for insane

Latin insanus, from in- + sanus sane

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Statistics for insane

Last Updated

9 Dec 2018

Look-up Popularity

Time Traveler for insane

The first known use of insane was circa 1550

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More Definitions for insane


in·​sane | \in-ˈsān \

Kids Definition of insane

1 : not normal or healthy in mind

2 : used by or for people who are insane an insane asylum

3 : very foolish or unreasonable

Other Words from insane

insanely adverb


in·​sane | \(ˈ)in-ˈsān \

Medical Definition of insane 


1 : exhibiting a severely disordered state of mind

2 : used by, typical of, or intended for insane persons an insane asylum

Other Words from insane

insanely adverb



Legal Definition of insane 

: affected with insanity

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More from Merriam-Webster on insane

Thesaurus: All synonyms and antonyms for insane

Spanish Central: Translation of insane

Nglish: Translation of insane for Spanish Speakers

Britannica English: Translation of insane for Arabic Speakers

Comments on insane

What made you want to look up insane? Please tell us where you read or heard it (including the quote, if possible).


to make faulty or ineffective

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