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definitions

insane

[ in-seyn ]
/ ɪnˈseɪn /
||
SEE MORE SYNONYMS FOR insane ON THESAURUS.COM

adjective

not sane; not of sound mind; mentally deranged.
of, relating to, or characteristic of a person who is mentally deranged: insane actions; an insane asylum.
utterly senseless: an insane plan.

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RELATED WORDS

crazy, irrational, paranoid, nuts, irresponsible, senseless, idiotic, preposterous, psychotic, mad, batty, bizarre, deranged, cracked, crazed, cuckoo, daft, demented, fatuous, frenzied

Nearby words

  1. ins,
  2. ins and outs,
  3. ins.,
  4. insalivate,
  5. insalubrious,
  6. insanely,
  7. insanitary,
  8. insanitation,
  9. insanity,
  10. insatiability

Origin of insane

From the Latin word insānus, dating back to 1550–60. See in-3, sane
Related formsin·sane·ly, adverbin·sane·ness, nounpseu·do·in·sane, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for insane

British Dictionary definitions for insane

insane

/ (ɪnˈseɪn) /

adjective

  1. mentally deranged; crazy; of unsound mind
  2. (as collective noun; preceded by the)the insane
characteristic of a person of unsound mindan insane stare
irresponsible; very foolish; stupid
Derived Formsinsanely, adverbinsaneness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for insane

insane

adj.

1550s, from Latin insanus "mad, insane; outrageous, excessive, extravagant," from in- "not" (see in- (1)) + sanus "well, healthy, sane" (see sane). Originally only of persons; of actions, from 1842. Cf. lunatic; and Italian pazzo "insane," originally a euphemism, from Latin patiens "suffering." German verrückt, literally past participle of verrücken "to displace," "applied to the brain as to a clock that is 'out of order' " [Buck]. The noun meaning "insane person" is attested from 1786.

Online Etymology Dictionary, © 2010 Douglas Harper
Medicine definitions for insane

insane

[ ĭn-sān′ ]

adj.

Of, exhibiting, or afflicted with insanity.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.