insanity

noun in·san·i·ty \ in-ˈsa-nə-tē \

|Updated on: 10 Jul 2018

Editor's Note: On the Meaning of insanity

Definition of insanity

plural insanities

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

3 a : extreme folly or unreasonableness

the insanity of violence

His comments were pure insanity.

b : something utterly foolish or unreasonable

the insanities of modern life

See insanity defined for English-language learners

See insanity defined for kids

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 of insanity from the Web

LeBron James will potentially enter free agency, setting up another summer of NBA offseason insanity.

— charles curtis, For The Win, "How the Celtics should convince LeBron James to sign with them," 29 June 2018
Neither could Golden State’s fans. Minutes after the pregame festivities ended, the usual parade of cars and trucks and double-decker buses rolled to the corner of 10th Street and Broadway, then took a left turn straight into insanity.

— al saracevic, San Francisco Chronicle, "Warriors throw a championship street party in Oakland," 12 June 2018
When holiday hosting is in full swing, storebought pie crust and rotisserie chicken help keep insanity at bay.

— kaitlyn yarborough, Southern Living, "What Does It Really Mean To Have Southern Taste?," 8 June 2018
Except it was overshadowed immediately by the other insanity that ensued.

— ben cohen, WSJ, "The Warriors Beat the Cavaliers, and Everything but the Score Was Bonkers," 1 June 2018
Our wives both deserve awards for staying supportive during that insanity.

— jay betsill, star-telegram, "Mark Cuban, Mount Everest and lots of radio: The journey of Ben and Skin | Fort Worth Star-Telegram," 17 May 2018
Once again, the internet multiverse has blessed us with another insanity-inducing audio illusion.

— andrew clark, Indianapolis Star, "Oh, no. There's a new yanny vs. laurel. Listen here.," 17 May 2018
During the trial, Romero claimed insanity as a defense for the murder and assault, Maricopa County officials said.

— nathan j. fish, azcentral, "Man sentenced to 17 years in prison for fatally stabbing Tilted Kilt co-worker," 11 May 2018
In legal proceedings, there is a difference between competency and insanity.

— emilie eaton, San Antonio Express-News, "Man accused of killing Elmendorf police chief is insane, experts say, reducing the likelihood of trial," 2 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.

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.

First Known Use of insanity

1590

in the meaning defined at sense 1

See Words from the same year

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insanity Synonyms

Other Psychology Terms

fetish, hypochondria, intelligence, mania, narcissism, neurosis, pathological, psychosis, schadenfreude, subliminal

INSANITY Defined for English Language Learners

insanity

noun

Definition of insanity for English Language Learners

: severe mental illness : the condition of being insane
: something that is very foolish or unreasonable

INSANITY Defined for Kids

insanity

noun in·san·i·ty \ in-ˈsa-nə-tē \

Definition of insanity for Students

: the condition of being abnormal or unhealthy in mind

Medical Dictionary

insanity

noun in·san·i·ty \ in-ˈsan-ət-ē \

medical Definition of insanity

plural insanities

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

Law Dictionary

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