Synonyms and related words :
aliene, ass, bedlamite, borderline case, crackbrain, crackpot, dement, demoniac, donkey, energumen, fanatic, flake, fou, idiot, imbecile, jackass, jerk, kook, loon, loony, lunatic, maniac, meshuggenah, nincompoop, ninny, non compos, noncompos, nut, phrenetic, psycho, psychopath, psychotic, raving lunatic, screwball, weirdo