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”; 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

Wilson started to struggle after eating his eighth chicken wing, which was coated in Da Bomb, Beyond Insanity hot sauce.

From Salon • Jun. 27, 2025

For many in F1 there is an aphorism that sums up Red Bull's approach to their second seat: "Insanity is doing the same thing over and over again and expecting different results."

From BBC • Mar. 25, 2025

“Whatever we are doing now isn’t working, and it needs to be corrected because, what is a statement? Insanity is doing things the same way over and over and expecting different results. It’s not working.”

From Washington Post • Jan. 27, 2023

Sarah Menkedick is the author of “Homing Instincts” and “Ordinary Insanity: Fear and the Silent Crisis of Motherhood in America.”

From New York Times • Aug. 23, 2022

When Inigo regained consciousness, it was still night on the Cliffs of Insanity.

From "The Princess Bride" by William Goldman

Related Words

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