The Collaborative International Dictionary of English v.0.48:
Polyphonous \Po*lyph"o*nous\, a. Same as Polyphonic. [1913 Webster]WordNet (r) 3.0 (2006):
polyphonous adj 1: of or relating to or characterized by polyphony; "polyphonic traditions of the baroque" [syn: polyphonic, polyphonous]