Synonyms and related words :
aliene, bedlamite, borderline case, crackpot, crank, cuckoo, dement, demoniac, ding-a-ling, energumen, fanatic, flake, fou, harebrain, idiot, kook, loon, loony, lunatic, madman, maniac, meshuggenah, noncompos, nut, phrenetic, raving lunatic, screwball, weirdo,