[1] : WordNet (r) 2.0

weirdo
     n 1: someone unpleasantly strange or eccentric syn: creep, weirdie,
           weirdy, spook
     2: someone deranged and possibly dangerous syn: crazy, loony,
         looney
see also:
creep weirdie weirdy spook crazy loony 
looney 

[2] : Moby Thesaurus II by Grady Ward, 1.0

33 moby thesaurus words for "weirdo":
   aliene, bedlamite, borderline case, character, crackbrain,
   crackpot, crank, dement, demoniac, eccentric, energumen, erratic,
   fanatic, flake, fou, freak, idiot, kook, loon, loony, lunatic,
   madman, maniac, meshuggenah, noncompos, nonconformist, nut,
   oddball, phrenetic, raving lunatic, recluse, screwball,
   strange duck

Weirdo >> W Words
Weirdo, definition of term: Weirdo
weirdo_pag1.html