adj causing insanity or madness.
2. insane ·adj used by, or appropriated to, insane persons; as, an insane hospital.
3. insane ·adj characterized by insanity or the utmost folly; chimerical; unpractical; as, an insane plan, attempt, ·etc.
4. insane ·adj exhibiting unsoundness or disorded of mind; not sane; mad; deranged in mind; delirious; distracted. ·see insanity, 2.