A three-part word (root 'sane', prefix 'in-' meaning 'not', suffix '-ity', meaning 'the state of'). Derived from Latin precursory equivalents.

• insane + -ity: insānus ("unhealthy; insane") + -itās

  Latin insānus, from in- + sanus ("sound, sane").

• in- + sanity: in- + sanitās

  Latin sanitās, from sānus + -itās.

• (America) IPA: /ɪnˈsænɪti/

insanity

1. The state of being insane; madness.

   Synonyms: Thesaurus:insanity

   Antonyms: Thesaurus:sanity

   Coordinate term: unsanity

   The defendant pleaded insanity in the hope of getting a reduced sentence.

   • 1837, L[etitia] E[lizabeth] L[andon], “The Chamber of Death”, in Ethel Churchill: Or, The Two Brides. […], volume III, London: Henry Colburn, […], →OCLC ↗, page 271 ↗:

     But the bed-side of Lady Marchmont had a darker lesson than the grave, the ravings of insanity revealed the fiery world of that beating and passionate heart. Ethel could only feel too fearful, too humbled, for judgment; but she wept, even while she prayed, beside her early friend.

• insane

• French: folie
• German: Wahnsinn
• Italian: follia, pazzia
• Portuguese: insanidade, loucura
• Russian: безу́мие
• Spanish: locura, insania, vesania