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

Synonyms & Antonyms On the Meaning of Insanity More Example Sentences Learn More about insanity

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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

Recent Examples on the Web

After being deemed unfit to travel for a Zenit training camp last year, Dzyuba posted an obligatory gym photo on Instagram, with a caption that included nothing more than William Henley’s ‘Invictus’. Glorious insanity. — SI.com, "Surprise World Cup Stars: Artem Dzyuba – The Russian Peter Crouch With an Infectious Smile," 9 July 2018 That’s what happened to Anthony Lynn, who profited from the insanity that follows Buddy Ryan & Sons. — Marcus Hayes, Philly.com, "Eagles assistant Duce Staley doesn't need your pity | Marcus Hayes," 6 July 2018 Much fitfully amusing, carefully choreographed insanity ensues when Quixote mistakes Toby for Sancho and drags him along on a manic getaway. — Justin Chang, latimes.com, "Terry Gilliam gets his long-overdue moment with ‘The Man Who Killed Don Quixote’ at Cannes," 20 May 2018 The defense is usually used in conjunction with insanity or self-defense claims. — NBC News, "Alleged 'gay panic defense' in Texas murder trial stuns advocates," 2 May 2018 The opportunity this November is not just to check this country’s slide into reality-show authoritarianism, but to destroy Ryan’s fiscal insanity for good and all. — Andrew Sullivan, Daily Intelligencer, "Pope Francis Isn’t Catholicism’s Trump," 20 Apr. 2018 The California band has remained true to its dark vision of death, suffering, punishment, insanity and chaos. — John Adamian, courant.com, "Slayer's Farewell Tour At Mohegan Sun," 26 May 2018 Wolfe, somehow, pulled off that high-wire feat of inhabiting his stories and transmitting their daring, their insanity, and their madcap joy without putting himself on the line in the process. — Corey Seymour, Vogue, "For Tom Wolfe, Affectation Was Armor," 15 May 2018 He and others choosing to leave Washington surely have additional motives, like escaping the current insanity and constant cross-fire which characterize their workplace. — Fred Niedner, chicagotribune.com, "Column: Which leaders will future voters look to?," 13 Apr. 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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Learn More about insanity

Dictionary Entries near insanity

Phrases Related to insanity

insanity plea

Statistics for insanity

Last Updated

16 Oct 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

See the full definition for insanity in the English Language Learners Dictionary

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

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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