'Insane' definitions:

Definition of 'insane'

From: WordNet
adjective
Afflicted with or characteristic of mental derangement; "was declared insane"; "insane laughter" [ant: sane]
adjective
Very foolish; "harebrained ideas"; "took insane risks behind the wheel"; "a completely mad scheme to build a bridge between two mountains" [syn: harebrained, insane, mad]

Definition of 'Insane'

From: GCIDE
  • Insane \In*sane"\, a. [L. insanus. See In- not, and Sane.]
  • 1. Exhibiting unsoundness or disorder of mind; not sane; mad; deranged in mind; delirious; distracted. See Insanity, 2. [1913 Webster]
  • 2. Used by, or appropriated to, insane persons; as, an insane hospital. [1913 Webster]
  • 3. Causing insanity or madness. [R.] [1913 Webster]
  • Or have we eaten on the insaneroot That takes the reason prisoner ? --Shak. [1913 Webster]
  • 4. Characterized by insanity or the utmost folly; chimerical; unpractical; as, an insane plan, attempt, etc. [1913 Webster]
  • I know not which was the insane measure. --Southey. [1913 Webster]

Synonyms of 'insane'

From: Moby Thesaurus