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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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

The sheer insanity of the situations that befall Cassius forces him to respond with wit, energy and reckless audacity, but the captivating stillness and melancholy cool that are among Stanfield’s defining traits as an actor never recede. Justin Chang, latimes.com, "Review: Boots Riley's 'Sorry to Bother You' is an arrestingly surreal satire on class rage and cultural identity," 5 July 2018 Fegely, 70, of Michigan City, has pleaded not guilty to the charges by reason of insanity. Amy Lavalley, Post-Tribune, "'Any junk science will be excluded,' judge in arson-murder trial says," 5 July 2018 USA TODAY Sports The World Cup’s Group B culminated in a few moments of insanity on Monday night, producing the kind of unpredictable, unthinkable drama that this tournament specializes in. Martin Rogers, USA TODAY, "Cristiano Ronaldo's missed penalty costs Portugal – and could haunt it forever," 25 June 2018 The possibility of an insanity defense resurfaced in early 2016. Rafael Olmeda, Sun-Sentinel.com, "Nine years later, no trial date for Hollywood ex-boxer who killed wife and stepson," 22 June 2018 The fact that this kind of rhetoric has become normalized, including in elite circles, is itself a kind of insanity. Matthew Yglesias, Vox, "The pernicious myth of “open borders”," 22 June 2018 Like awakening to the insanity of what’s happening, and so everything from the letter Laura Bush sent to all kinds of leaders in the church community saying Wait a minute, this is outrageous. Rebecca Traister, The Cut, "Cages, ‘Infestations,’ and the Demonization of Immigrants," 27 June 2018 Really, this is the insanity of what’s being promoted as the next big mobility trend in America. Ed Wallace, star-telegram, "Promises, Promises," 22 June 2018 During that earlier period of tech wealth accumulation known as the dotcom era, the Baffler was a reliable source of scabrous insight into the collective insanity of the times. Stephen Phillips, SFChronicle.com, "New tech books: ‘Bad Blood,’ ‘Live Work Work Work Die,’ ‘The Efficiency Paradox’," 22 June 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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Phrases Related to insanity

insanity plea

Statistics for insanity

Last Updated

4 Sep 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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