insanity

[ in-san-i-tee ]
/ ɪnˈsæn ɪ ti /

noun, plural in·san·i·ties.

the condition of being insane; a derangement of the mind.
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.
Psychiatry. (formerly) psychosis.
  1. extreme foolishness; folly; senselessness; foolhardiness: 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.

Origin of insanity

From the Latin word insānitās, dating back to 1580–90. See in-3, sanity
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for insanity

British Dictionary definitions for insanity

insanity

/ (ɪnˈsænɪtɪ) /

noun plural -ties

relatively permanent disorder of the mind; state or condition of being insane
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
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

Medicine definitions for insanity

insanity

[ ĭn-sănĭ-tē ]

n.

Persistent mental disorder or derangement. Not in scientific use.
Unsoundness of mind sufficient in the judgment of a civil court to render a person unfit to maintain a contractual or other legal relationship or to warrant commitment to a mental health facility.
In most criminal jurisdictions, a degree of mental malfunctioning considered to be sufficient to relieve the accused of legal responsibility for the act committed.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.