Source : Webster's Revised Unabridged Dictionary (1913)

Anonym \An"o*nym\, n. [F. anonyme. See {Anonymous}.]
   1. One who is anonymous; also sometimes used for
      ``pseudonym.''

   2. A notion which has no name, or which can not be expressed
      by a single English word. [R.] --J. R. Seeley.

Source : WordNet®

anonym
     n : a fictitious name used when the person performs a particular
         social role [syn: {pseudonym}, {nom de guerre}]