nom de guerre

from WordNet (r) 3.0 (2006)

nom de guerre
    n 1: a fictitious name used when the person performs a
         particular social role [syn: {pseudonym}, {anonym}, {nom de
         guerre}]

from The Collaborative International Dictionary of English v.0.48

Nom \Nom\, n. [F. See {Noun}.]
   Name.
   [1913 Webster]

   {Nom de guerre}, literally, war name; hence, a fictitious
      name, or one assumed for a time.

   {Nom de plume}, literally, pen name; hence, a name assumed by
      an author as his or her signature.
      [1913 Webster]