Etymologically
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insanity

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Pronunciation

  • US: /ɪnˈsænɪti/[1]

Etymology

It is borrowed from Latin īnsānitās (“unsoundness, especially of the mind”),[2][3][4][5] from īnsānus (“mad, insane”) and the noun suffix -tās;[2][3][4] the adjective is the source of insane, and is formed from in- (“not”) and sānus (“sound, healthy”).[3][6] In Latin īnsānitās meant unhealthiness or unsoundness, while the usual noun for madness was īnsānia.[3] The OED compares French insanité, recorded only from 1784.[2]

Earliest recorded meaning

The condition of being insane: 1590, in Swinburne's treatise on wills and testaments.[2] Etymonline dates it to the 1580s[3] and Merriam-Webster to 1650.[7]

Semantic evolution

The word entered English in a legal treatise, and the law kept a sense of its own: an unsoundness of mind that removes a person's capacity to make a contract or their criminal responsibility, as in not guilty by reason of insanity.[2][8][9][10] The weakened sense of extreme folly or senselessness is recorded from 1651 in the OED,[2] but only from 1844 in Etymonline.[3] In medicine the word has become an outmoded term for severe mental illness.[6][9]

Timeline

  • 1590 – the condition of being insane.[2]
  • 1651 – extreme imprudence or senselessness; an instance of this.[2]

Modern meaning

Noun

  1. Severe mental illness; madness.
  2. (law) Unsoundness of mind that makes a person unfit to enter into a contract, or not responsible for a crime: She was found not guilty by reason of insanity.
  3. Extreme folly or irrationality, or an act that shows it: It would be insanity to drive across the desert without water.

Usage notes

The American Heritage Dictionary notes that the word is not used in psychiatric diagnosis,[9] Stedman's calls it an outmoded term for severe mental illness or psychosis,[6] and Merriam-Webster labels the medical sense dated.[7]

References

  1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e f g h Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  3. ^ a b c d e f Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  4. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
  5. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
  6. ^ a b c Stedman's Medical Dictionary, Baltimore: Lippincott Williams & Wilkins
  7. ^ a b Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  8. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  9. ^ a b c The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  10. ^ Collins English Dictionary (2023), Glasgow: HarperCollins