insanity

noun
in·​san·​i·​ty | \in-ˈsa-nə-tē \
plural insanities

Definition of insanity 

1 dated : a severely disordered state of the mind usually occurring as a specific disorder

2 law : unsoundness of mind or lack of the ability to understand that prevents one from having the mental capacity required by law to enter into a particular relationship, status, or transaction or that releases one from criminal or civil responsibility

3a : extreme folly or unreasonableness the insanity of violence His comments were pure insanity.

b : something utterly foolish or unreasonable the insanities of modern life

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Synonyms & Antonyms for insanity

Synonyms

aberration, dementia, derangement, lunacy, madness, mania, rage [archaic]

Antonyms

mind, saneness, sanity

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On the Meaning of Insanity

An oft-quoted bon mot (frequently attributed to Albert Einstein, Benjamin Franklin, or a number of other people who probably never said it) is that insanity may be defined as “doing the same thing over and over and expecting different results.” While the job of lexicographers might be easier if they were allowed to use witty sayings instead of precise definitions, such belletristic labors are not within their purview. The straight facts about insanity are these: it has been in use in English since the late 16th century, for the first two hundred years or so carrying only the literal meaning “the condition of being mentally deranged.” In the 19th century it began to take on a looser sense, “extreme folly or unreasonableness.” In modern usage, insanity may be found in both senses: you may tell your brother that trying to skateboard while holding onto a car is "insanity" (in which case you mean that it is extremely foolish) or encounter the stricter original meaning in such contexts as insanity plea.

Examples of insanity in a Sentence

She was found not guilty by reason of insanity. His friends thought his decision to quit his job was pure insanity. Please, no more violence. It's time to stop this insanity. the insanities of modern life
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Recent Examples on the Web

Many of these women had to plead insanity or say their pregnancy was causing them to consider suicide — two of the few permissible justifications for obtaining permission. Rickie Solinger, Vox, "This is what life was like for women in America before Roe v. Wade," 7 Sep. 2018 Other characters from across the Mario universe make their own cameos across the script’s nearly 90 pages of insanity. Shoshana Wodinsky, The Verge, "This masterpiece is not the Waluigi movie script we want, but it’s the one we deserve," 17 Aug. 2018 Cruz has not signaled any intent to plead insanity. Rafael Olmeda, Sun-Sentinel.com, "Defense moves to block release of Parkland shooter's confession," 7 June 2018 To assess whether a defendant can plead insanity, judges rely on medical experts. Jayme Fraser, The Malheur Enterprise, idahostatesman, "Doctors warned that Oregon killer, rapist would attack again. The state released him. | Idaho Statesman," 6 May 2018 To assess whether a defendant can plead insanity, judges rely on medical experts. Special To The Oregonian, OregonLive.com, "Oregon failed to protect public from killer found 'guilty except for insanity'," 25 Apr. 2018 Worley had initially pleaded not guilty and had planned to plead insanity, the Indianapolis Star reported. Kc Baker, PEOPLE.com, "Ind. Mom Who Murdered Her Kids and Gave 'Matter-of-Fact' Confession to 911 Gets 120 Years," 20 Mar. 2018 Five questions, then, as the insanity is about to begin: Does LeBron affect the Suns? Scott Bordow, azcentral, "Phoenix Suns: Five questions as NBA free agency approaches," 29 June 2018 To put this insanity into context, Bird is less than a year old….potentially the fastest company ever to gain unicorn status. Polina Marinova, Fortune, "Term Sheet -- Wednesday, May 30," 30 May 2018

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

1590, in the meaning defined at sense 1

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Statistics for insanity

Last Updated

11 Dec 2018

Look-up Popularity

Time Traveler for insanity

The first known use of insanity was in 1590

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More Definitions for insanity

insanity

noun

English Language Learners Definition of insanity

: severe mental illness : the condition of being insane

: something that is very foolish or unreasonable

insanity

noun
in·​san·​i·​ty | \in-ˈsa-nə-tē \

Kids Definition of insanity

: the condition of being abnormal or unhealthy in mind

insanity

noun
in·​san·​i·​ty | \in-ˈsan-ət-ē \
plural insanities

Medical Definition of insanity 

1 dated : a severely disordered state of the mind usually occurring as a specific disorder

2 law : unsoundness of mind or lack of the ability to understand that prevents one from having the mental capacity required by law to enter into a particular relationship, status, or transaction or that releases one from criminal or civil responsibility

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insanity

noun
in·​san·​i·​ty

Legal Definition of insanity 

1 : unsoundness of mind or lack of the ability to understand that prevents one from having the mental capacity required by law to enter into a particular relationship, status, or transaction or that releases one from criminal or civil responsibility: as

a : a disease, defect, or condition of the mind that renders one unable to understand the nature of a criminal act or the fact that it is wrong or to conform one's conduct to the requirements of the law being violated

b : inability to understand and participate in legal proceedings brought against one : incompetence

c : inability to understand the nature and purpose of a punishment (as the death penalty) to which one has been sentenced

d : inability to understand the nature and consequences of one's acts (as making a will) or of events, matters, or proceedings in which one is involved — see also commitment, durham rule, irresistible impulse test, m'naghten test, not guilty by reason of insanity, substantial capacity test — compare capacity, competency, competent, diminished capacity, sanity

2 : the affirmative defense of having acted while insane

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Comments on insanity

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