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

Example Sentences

This allows events to balloon beyond our comprehension, and may be preventing us from stopping this insanity.

From Salon • Mar. 25, 2026

An IT specialist working for MI5 on a contract who disclosed intelligence information to a "foreign power" has been found "not guilty by reason of insanity" by an Old Bailey jury.

From BBC • Mar. 20, 2026

That flying blob of insanity isn’t for everyone.

From The Wall Street Journal • Feb. 16, 2026

“I don’t get where all this insanity is coming from.”

From MarketWatch • Feb. 3, 2026

Montag's hand closed like a mouth, crushed the book with wild devotion, with an insanity of mindlessness to his chest.

From "Fahrenheit 451" by Ray Bradbury

Related Words

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