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.

---

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

---

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

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 entire pseudo-event was one one of those blink-and-you-miss-it moments that get drowned out in the endless baying insanity of our collective reality.

From Salon • Feb. 28, 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

As compared with last year there was more food, more clothes, more houses, more furniture, more cooking pots, more fuel, more ships, more helicopters, more books, more babies—more of everything except disease, crime, and insanity.

From "1984" by George Orwell

Related Words

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