cacodemon

from WordNet (r) 3.0 (2006)

cacodemon
    n 1: an evil spirit [syn: {cacodemon}, {cacodaemon}] [ant:
         {eudaemon}, {eudemon}, {good spirit}]

from The Collaborative International Dictionary of English v.0.48

Cacodemon \Cac`o*de"mon\, n. [Gr. ??????????; kako`s bad +
   ?????? demon: cf. F. cacod['e]mon.]
   1. An evil spirit; a devil or demon. --Shak.
      [1913 Webster]

   2. (Med.) The nightmare. --Dunaglison.
      [1913 Webster]