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insane

[in-seyn]
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adjective
  1. not sane; not of sound mind; mentally deranged.
  2. of, relating to, or characteristic of a person who is mentally deranged: insane actions; an insane asylum.
  3. utterly senseless: an insane plan.
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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

Synonyms

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1. demented; lunatic, crazed, crazy; maniacal. 3. foolish, irrational. See mad.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for insane

Contemporary Examples

Historical Examples

  • Schwitter, the nurseryman, had proved to have a wife in an insane asylum.

    K

    Mary Roberts Rinehart

  • The adoration of her, and the insane desire of her, can be seen in every play he wrote from 1597 to 1608.

  • Advocated with more heat than light by the outmates of every asylum for the insane.

  • He, and he alone, in this insane city, will wait at table (the Chinaman doesn't count).

    American Notes

    Rudyard Kipling

  • And the fancy was this: Are not the sane and the insane equal at night as the sane lie a dreaming?

British Dictionary definitions for insane

insane

adjective
    1. mentally deranged; crazy; of unsound mind
    2. (as collective noun; preceded by the)the insane
  2. characteristic of a person of unsound mindan insane stare
  3. irresponsible; very foolish; stupid
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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

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.

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Online Etymology Dictionary, © 2010 Douglas Harper
insane in Medicine

insane

(ĭn-sān′)
adj.
  1. Of, exhibiting, or afflicted with insanity.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.