insanity

American  

[in-san-i-tee] / ɪnˈsæn ɪ ti /

noun

plural

insanities

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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Etymology

Origin of insanity

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

The New York Post's Lauren Sarner called the new season "an unhinged disaster" and "an off-the-rails roller coaster of insanity".

From BBC • Apr. 13, 2026

It’s positively demented, but it’s not insanity for insanity’s sake.

From Salon • Apr. 5, 2026

In June 1982, Hinckley was found not guilty by reason of insanity and sent to a psychiatric facility; he was fully released from federal custody in 2022.

From The Wall Street Journal • Mar. 30, 2026

Others have been declared not guilt by reason of insanity, while others are in conservatorship.

From Los Angeles Times • Mar. 6, 2026

I thought talking and not talking made the difference between sanity and insanity.

From "The Woman Warrior" by Maxine Hong Kingston

Related Words

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