Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Scrabble
  • Spanish Central
  • Learner's Dictionary

insanity

play
noun, in·san·i·ty \in-ˈsa-nə-tē\

Simple Definition of insanity

  • : severe mental illness : the condition of being insane

  • : something that is very foolish or unreasonable

Source: Merriam-Webster's Learner's Dictionary

Full Definition of insanity

plural insanities

  1. 1 :  a deranged state of the mind usually occurring as a specific disorder (as schizophrenia)

  2. 2 :  such unsoundness of mind or lack of understanding as prevents one from having the mental capacity required by law to enter into a particular relationship, status, or transaction or as removes one from criminal or civil responsibility

  3. 3 a :  extreme folly or unreasonableness b :  something utterly foolish or unreasonable

Examples of insanity in a sentence

  1. She was found not guilty by reason of insanity.

  2. His friends thought his decision to quit his job was pure insanity.

  3. Please, no more violence. It's time to stop this insanity.

  4. the insanities of modern life



1590

First Known Use of insanity

1590

Rhymes with insanity



INSANITY Defined for Kids

insanity

play
noun in·san·i·ty \in-ˈsa-nə-tē\

Definition of insanity for Students

  1. :  the condition of being abnormal or unhealthy in mind




Medical Dictionary

insanity

play
noun in·san·i·ty \in-ˈsan-ət-ē\

Medical Definition of insanity

plural insanities

  1. 1dated :  a severely disordered state of the mind usually occurring as a specific disorder

  2. 2law :  unsoundness of mind or lack of the ability to understand that prevents one from having the mental capacity required by law to enter into a particular relationship, status, or transaction or that releases one from criminal or civil responsibility




Law Dictionary

insanity

noun in·san·i·ty

Legal Definition of insanity

  1. 1 :  unsoundness of mind or lack of the ability to understand that prevents one from having the mental capacity required by law to enter into a particular relationship, status, or transaction or that releases one from criminal or civil responsibility: as a :  a disease, defect, or condition of the mind that renders one unable to understand the nature of a criminal act or the fact that it is wrong or to conform one's conduct to the requirements of the law being violated b :  inability to understand and participate in legal proceedings brought against one :  incompetence c :  inability to understand the nature and purpose of a punishment (as the death penalty) to which one has been sentenced d :  inability to understand the nature and consequences of one's acts (as making a will) or of events, matters, or proceedings in which one is involved — see also commitment, durham rule, irresistible impulse test, m'naghten test, not guilty by reason of insanity, substantial capacity test — compare capacity, competency, competent, diminished capacity, sanity

  2. 2 :  the affirmative defense of having acted while insane





Seen and Heard

What made you want to look up insanity? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

a timid, meek, or unassertive person

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

alt-5746713d76276

Which of these is a synonym of nonplus?

soothe perplex disapprove reduce
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ