Insane \In*sane"\, a. [L. insanus. See In- not, and Sane.]

1. Exhibiting unsoundness or disorded of mind; not sane; mad; deranged in mind; delirious; distracted. See Insanity, 2.

2. Used by, or appropriated to, insane persons; as, an insane hospital.

3. Causing insanity or madness. [R.]

Or have we eaten on the insaneroot That takes the reason prisoner ? --Shak.

4. Characterized by insanity or the utmost folly; chimerical; unpractical; as, an insane plan, attempt, etc.

I know not which was the insane measure. --Southey.

Source: Webster's Revised Unabridged Dictionary (1913)