The Collaborative International Dictionary of English v.0.48:

Homonym \Hom"o*nym\, n. [Cf. F. homonyme. See Homonymous.]
   A word having the same sound as another, but differing from
   it in meaning; as the noun bear and the verb bear. [Written
   also homonyme.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

homonym
    n 1: two words are homonyms if they are pronounced or spelled
         the same way but have different meanings

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "homonym":
   Doppelganger, actual thing, antonym, articulation, carbon copy,
   copy, dead ringer, ditto, double, duplicate, equivalent,
   exact counterpart, expression, facsimile, free form, homograph,
   homophone, idem, identical same, lexeme, linguistic form, locution,
   logos, metonym, minimum free form, monosyllable, no other,
   none other, polysyllable, replica, selfsame, spit and image,
   spitting image, syllable, synonym, term, the same,
   the same difference, twin, usage, utterance, verbalism, verbum,
   very image, very same, vocable, word