insanity

noun
in·​san·​i·​ty | \ in-ˈsa-nə-tē How to pronounce insanity (audio) \
plural insanities

Definition of insanity

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

Keep scrolling for more

Synonyms & Antonyms for insanity

Synonyms

Antonyms

Visit the Thesaurus for More 

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.

Examples of insanity in a Sentence

She was found not guilty by reason of insanity. His friends thought his decision to quit his job was pure insanity. Please, no more violence. It's time to stop this insanity. the insanities of modern life
See More
Recent Examples on the Web If jurors found Riley not guilty by reason of insanity, the judge would then decide whether he should be committed to a mental hospital, provided other forms of treatment or simply released. orlandosentinel.com, 12 Oct. 2021 Hinckley tried to assassinate President Reagan in 1981, was found not guilty by reason of insanity and spent nearly 30 years at a mental facility. Aj Willingham, CNN, 28 Sep. 2021 In 1982, a jury found Mr. Hinckley not guilty by reason of insanity. New York Times, 27 Sep. 2021 Jimenez, 20, pleaded not guilty by reason of insanity to two counts of murder on Monday, John Hall, a spokesperson for the Riverside County District Attorney's Office, confirms to PEOPLE. Gabrielle Chung, PEOPLE.com, 27 Sep. 2021 In 1982, a jury found Hinckley not guilty by reason of insanity. BostonGlobe.com, 27 Sep. 2021 Jurors found Hinckley not guilty by reason of insanity. Paulina Smolinski, CBS News, 27 Sep. 2021 In California, defendants found not guilty by reason of insanity still must be treated in a state mental hospital. Laura Anaya-morga, Los Angeles Times, 27 Sep. 2021 The fans, those screaming creators of culture, those lightning strikes of insanity, were the stars of Penn State’s 28-20 victory against the Tigers. Joseph Goodman | Jgoodman@al.com, al, 22 Sep. 2021

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.

See More

First Known Use of insanity

1590, in the meaning defined at sense 1

Keep scrolling for more

Learn More About insanity

Time Traveler for insanity

Time Traveler

The first known use of insanity was in 1590

See more words from the same year

Dictionary Entries Near insanity

insanitary

insanity

insanity plea

See More Nearby Entries 

Statistics for insanity

Last Updated

16 Oct 2021

Cite this Entry

“Insanity.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/insanity. Accessed 19 Oct. 2021.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

Keep scrolling for more

More Definitions for insanity

insanity

noun

English Language Learners Definition of insanity

: severe mental illness : the condition of being insane
: something that is very foolish or unreasonable

insanity

noun
in·​san·​i·​ty | \ in-ˈsa-nə-tē How to pronounce insanity (audio) \

Kids Definition of insanity

: the condition of being abnormal or unhealthy in mind

insanity

noun
in·​san·​i·​ty | \ in-ˈsan-ət-ē How to pronounce insanity (audio) \
plural insanities

Medical Definition of insanity

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

Keep scrolling for more

insanity

noun
in·​san·​i·​ty

Legal Definition of insanity

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 : the affirmative defense of having acted while insane

More from Merriam-Webster on insanity

Nglish: Translation of insanity for Spanish Speakers

Britannica English: Translation of insanity for Arabic Speakers

Britannica.com: Encyclopedia article about insanity

WORD OF THE DAY

Test Your Vocabulary

Difficult Spelling Words Quiz

  • alphabet pasta spelling help
  • Which is the correct spelling?
Spell It

Can you spell these 10 commonly misspelled words?

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!