insanity

play
noun in·san·i·ty \in-ˈsa-nə-tē\

Definition of insanity

plural

insanities

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

  2. 2 law :  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

  3. 3a :  extreme folly or unreasonableness the insanity of violence His comments were pure insanity.b :  something utterly foolish or unreasonable the insanities of modern life

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

Recent Examples of insanity from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'insanity.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

On the Meaning of insanity

An oft-quoted bon mot (frequently attributed to Albert Einstein, Benjamin Franklin, or a number of other people who probably never said it) is that insanity may be defined as “doing the same thing over and over and expecting different results.” While the job of lexicographers might be easier if they were allowed to use witty sayings instead of precise definitions, such belletristic labors are not within their purview. The straight facts about insanity are these: it has been in use in English since the late 16th century, for the first two hundred years or so carrying only the literal meaning “the condition of being mentally deranged.” In the 19th century it began to take on a looser sense, “extreme folly or unreasonableness.” In modern usage, insanity may be found in both senses: you may tell your brother that trying to skateboard while holding onto a car is "insanity" (in which case you mean that it is extremely foolish) or encounter the stricter original meaning in such contexts as insanity plea.

First Known Use of insanity

1590



INSANITY Defined for English Language Learners

insanity

play
noun

Definition of insanity for English Language Learners

  • : severe mental illness : the condition of being insane

  • : something that is very foolish or unreasonable


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).

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

an extremely thin woman

Get Word of the Day daily email!

Test Your Vocabulary

Time Traveler Quiz: Which Word Came First?

  • time-traveler-quiz-which-word-came-first
  • Which came first?
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
Word Winder's CrossWinder

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

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!