Synonyms: Crazy, mad, demented, lunatic, irrational, wild, daft, loony, deranged, foolish
Antonyms: Sane, rational, sound, balanced, normal, realistic, healthy, sensible, wise, logical
1. In a state of mind which prevents normal perception, behaviour, or social interaction; seriously mentally ill.
2. Extremely foolish; irrational.
3. Shocking; outrageous.
The king became insane after the death of his beloved wife.