[ in-san-i-tee ]
See synonyms for insanity on
noun,plural in·san·i·ties.
  1. (not in technical use as a medical diagnosis) the condition of being insane; a derangement of the mind.

  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.

  1. Psychiatry. (formerly) psychosis.

    • extreme foolishness: Trying to drive through that traffic would be pure insanity.

    • a foolish or senseless action, policy, statement, etc.: We've heard decades of insanities in our political discourse.

Origin of insanity

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

Other words for insanity

Words Nearby insanity Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use insanity in a sentence

British Dictionary definitions for insanity


/ (ɪnˈsænɪtɪ) /

nounplural -ties
  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

  1. utter folly; stupidity

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012