insanity

A three-part word (root 'sane', prefix 'in-' meaning 'not', suffix '-ity', meaning 'the state of'). Derived from Latin precursory equivalents. Two possible candidates for construction order:

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

  Latin insānus (“unsound in mind; mad, insane”), from in- + sanus (“sound, sane”). Modern forms of roots: in- + sane

• in- +‎ sanity: in- (“lacking; without”) +‎ sanitās (“health; sanity”)

  Latin sanitās (“sound in mind; sane”), from sānus + -itās. Modern forms of roots: sane + -ity

• (US) IPA^(key): /ɪnˈsænɪti/

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insanity (countable and uncountable, plural insanities)

1. The state of being insane; madness.

   Synonyms: see Thesaurus:insanity

   Antonyms: see 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