insanity

American  

[in-san-i-tee] / ɪnˈsæn ɪ ti /

noun

• insanities
  plural

1. (not in technical use as a medical diagnosis) the condition of being insane; a derangement of the mind.

   Synonyms:

   madness, lunacy, aberration, mania, craziness

2. Law. such unsoundness of mind as frees one from legal responsibility, as for committing a crime, or as signals one's lack of legal capacity, as for entering into a contractual agreement.

3. Psychiatry. (formerly) psychosis.

4. 1. extreme foolishness.

      Trying to drive through that traffic would be pure insanity.

   2. a foolish or senseless action, policy, statement, etc..

      We've heard decades of insanities in our political discourse.

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insanity British  

/ ɪnˈsænɪtɪ /

noun

1. relatively permanent disorder of the mind; state or condition of being insane

2. law a defect of reason as a result of mental illness, such that a defendant does not know what he or she is doing or that it is wrong

3. utter folly; stupidity

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Other Word Forms

Noun Inflected Forms

• insanities
  plural

Etymology

Origin of insanity

First recorded in 1580–90; from Latin insānitāt-, stem of insānitās “unsoundness of mind, insanity”; see origin at in- ³, sanity

Explanation

Insanity is an ongoing state of extreme mental illness, which may cause abnormal or antisocial behaviors. If you bark at cats and meow at dogs, you might suffer from insanity. The noun insanity originates from the Latin word insanitatem, meaning "unhealthfulness" relating to the mind. It is believed that master artist Vincent van Gogh, who cut off his ear and gave it to a prostitute, experienced periods of insanity. But this term can also refer to things people perceive as unconventional or foolish, like your neighbor who quit his job, sold all his belongings, and bought a boat to sail around the world.

Example Sentences

See Examples For:

insanity insanities

Lawrence, a troubled man who thought himself the heir to the British throne, was found not guilty by reason of insanity.

From The Wall Street Journal ● Jul. 24, 2026

Mangione's lawyers will argue that he was suffering from an "extreme emotional disturbance" -- a partial defense that can reduce a sentence, unlike an insanity plea, which seeks to avoid criminal responsibility altogether.

From Barron's ● Jun. 17, 2026

Isn’t there a saying about insanity is repeating the same mistakes over and over and expecting a different result?

From Los Angeles Times ● Jun. 6, 2026

When “Dude, Where’s My Car?” or “Pineapple Express” pushes the insanity to its limit, the films feel like testaments to close friendship.

From Salon ● Apr. 18, 2026

What insanity had made her get Ethel floated?

From "East of Eden" by John Steinbeck

I wailed, the aggravations, wasted hours and general insanities of technology culminating in that one moment.

From Seattle Times ● Aug. 18, 2023

We will eventually turn it toxic, as we put all of the various cultural insanities under that brand category,” Rufo wrote.

From Washington Post ● Jun. 19, 2021

So maddeningly complex is the system, so many its perversions, that we will take our time spooling out the insanities and inequities one by one in future columns.

From Washington Times ● Oct. 10, 2018

The conventional advice column is about gawking at car crashes, delighting in the contrast between the sensible advice giver and the insanities endured or perpetrated by the LW.

From Slate ● Jul. 5, 2016

Lee said softly, “Couldn’t a world be built around accepted truth? Couldn’t some pains and insanities be rooted out if the causes were known?”

From "East of Eden" by John Steinbeck

Related Words

• absurdity
• alienation
• craziness
• folly
• frenzy
• hysteria
• irresponsibility
• lunacy
• madness
• mental disorder