Synonyms and related words :
alien, aliene, bedlamite, borderline case, case, character, crackbrain, crackpot, crank, cuckoo, dement, demoniac, ding-a-ling, eccentric, energumen, erratic, fanatic, flake, fou, freak, harebrain, hermit, hobo, idiot, lone wolf, loner, loon, loony, lunatic, madman, maniac, maverick, meshuggenah, natural, noncompos, nonconformist, nut, odd fellow, oddball, oddity, original, outsider, pariah, phrenetic, queer duck, queer fish, queer specimen, rara avis, raving lunatic, recluse, screwball, solitary, strange duck, tramp, type, weirdo, zealot