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.

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 for insane Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for insaner

Historical Examples of insaner

British Dictionary definitions for insaner


    1. mentally deranged; crazy; of unsound mind
    2. (as collective noun; preceded by the)the insane
  1. characteristic of a person of unsound mindan insane stare
  2. 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 insaner



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

insaner in Medicine


  1. 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.