Source : Webster's Revised Unabridged Dictionary (1913)

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

   2. (Med.) The nightmare. --Dunaglison.

Source : WordNet®

cacodemon
     n : an evil spirit [syn: {cacodaemon}] [ant: {eudemon}]