Source : Webster's Revised Unabridged Dictionary (1913)

Autonomasy \Au`to*nom"a*sy\, n. [Auto- + Gr. ? a name, fr. ? a
   name; or for E. antonomasia.] (Rhet.)
   The use of a word of common or general signification for the
   name of a particular thing; as, ``He has gone to town,'' for,
   ``He has gone to London.''