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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Synonyms & Antonyms for insanity

Synonyms

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

Antonyms

mind, saneness, sanity

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

Maryland’s version of an insanity defense, citing a mental disorder. — Washington Post, "Lawyers for accused Capital Gazette shooter ask judge to sanction prosecutors," 5 Sep. 2019 The prosecution and defense agreed to take the death penalty off the table if Oberhansley's attorneys agreed not to use insanity as a defense. — Kala Kachmar, The Courier-Journal, "Prosecutor: Cannibalism victim was butchered 'like you wouldn't kill a livestock animal'," 21 Aug. 2019 Dahmer was charged in 15 of the killing and his trial began in early 1992, with his lawyers arguing insanity as their defense. — Chris Harris, PEOPLE.com, "A Brief History of Some of America's Most Notorious Televised Trials," 20 Aug. 2019 Like some classic Edgar Allan Poe character, his perfectly reasonable introduction gradually simmers to a full-on boil of criminal insanity. — Ron Charles, Dallas News, "'The Doll Factory' is a page-turning Victorian thriller," 13 Aug. 2019 But the gun violence source is rooted in a cultural bipolar insanity. — Letters To The Editor, The Mercury News, "Letter: Violence rooted in cultural bipolar insanity," 7 Aug. 2019 Prison inmates have been diagnosed with insanity while incarcerated there or already existing conditions of mental illness have worsened, according to a 2012 class-action lawsuit against the U.S. Bureau of Prisons. — Kirk Mitchell, The Denver Post, "Colorado’s Supermax prison now occupied by El Chapo is “worse than death,” ex-warden said," 27 July 2019 Erickson later claimed to have faked insanity to beat the possession rap, which would have meant a sentence between two years and life. — Tom Maxwell, Longreads, "Remembering Roky Erickson," 7 June 2019 The above synopsis is just a small taste of the true insanity that unfolds during the premiere. — Christopher Rosa, Glamour, "Riverdale's Cult Plot Is the Only Thing I Care About Right Now," 10 Oct. 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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Statistics for insanity

Last Updated

18 Sep 2019

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

2 : the affirmative defense of having acted while insane