Insane | Definition of insane by Merriam-Webster

Definition of INSANE

1

: mentally disordered : exhibiting insanity

2

: used by, typical of, or intended for insane persons <an insane asylum>

3

: absurd <an insane scheme for making money>

4

: extreme 1

— in·sane·ly adverb

— in·sane·ness \-ˈsān-nəs\ noun

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Latin insanus, from in- + sanus sane

First Known Use: circa 1550

Synonyms: balmy, barmy [chiefly British], bats, batty, bedlam, bonkers, brainsick, bughouse [slang], certifiable, crackbrained, cracked, crackers, crackpot, cranky [dialect], crazed, crazy, cuckoo, daffy, daft, demented, deranged, fruity [slang], gaga, haywire, kooky (also kookie), loco [slang], loony (also looney), loony tunes (or looney tunes), lunatic, mad, maniacal (also maniac), mental, meshuga (or meshugge also meshugah or meshuggah), moonstruck, non compos mentis, nuts, nutty, psycho, psychotic, scatty [chiefly British], screwy, unbalanced, unhinged, unsound, wacko (also whacko), wacky (also whacky), wud [chiefly Scottish], around the bend, off one's gourd, off one's head, off one's rocker, out of one's head (or mind), out to lunch [slang]

1

: not normal or healthy in mind

2

: used by or for people who are insane <an insane asylum>

3

: very foolish or unreasonable

— in·sane·ly adverb

1

: mentally disordered : exhibiting insanity

2

: used by, typical of, or intended for insane persons <an insane asylum>

—in·sane·ly adverb

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