Pronunciation: (in-sān'), [key]
1. not sane; not of sound mind; mentally deranged.
2. of, pertaining to, or characteristic of a person who is mentally deranged: insane actions; an insane asylum.
3. utterly senseless: an insane plan.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.