Source : Webster's Revised Unabridged Dictionary (1913)

Polyphonic \Pol`y*phon"ic\, a. [Gr. ?; poly`s many + ? sound:
   cf. F. polyphone.]
   1. Having a multiplicity of sounds.

   2. Characterized by polyphony; as, Assyrian polyphonic
      characters.

   3. (Mus.) Consisting of several tone series, or melodic
      parts, progressing simultaneously according to the laws of
      counterpoint; contrapuntal; as, a polyphonic composition;
      -- opposed to {homophonic}, or {monodic}.

Source : WordNet®

polyphonic
     adj 1: having two or more phonetic values; "polyphonic letters such
            as `a'"
     2: of or relating to or characterized by polyphony; "polyphonic
        traditions of the baroque" [syn: {polyphonous}]
     3: having two or more independent but harmonically related
        melodic parts sounding together [syn: {contrapuntal}]
        [ant: {monophonic}]