Polyphonymusical texture consisting of several independent melodic voices, as opposed to music with just one voice (monophony) or music with one dominant melodic voice accompanied by chordss (homophony).
The term is usually used in reference to music of the late Middle Ages and Renaissance - Baroque forms such as the fugue which might be called polyphonic are usually described instead as contrapuntal. Also, as opposed to the species terminology of counterpoint, polyphony was generally either "pitch-against-pitch"/"point-against-point" or "sustained-pitch" in one part with melismas of varying lengths in another (van der Werf, 1997). In all cases the conception was likely what Margaret Bent (1999) calls "dyadic counterpoint", with each part being written generally against one other part, with all parts modified if needed in the end. This point-against-point conception is opposed to "successive composition", where voices were written in an order with each new voice fitting into the whole so far constructed, which was previously assumed.
More generally, the word can mean the simultaneous sounding of more than one note; hence, a polyphonic synthesiser is one capable of playing more than one note at a time. Such an instrument capable of playing, say, 16 notes at once is said to have 16 voice polyphony.
Two treatsies, both dating from c. 900, are usually consider the oldest surviving part-music though they are note-against-note and voices move mostly in parallel octaves, fifths, and fourths and not intended to be performed. The 'Winchester Tropers', from c. 1000, are the oldest surviving example of practical rather than pedagogical polyphony, though intervals, pitch levels, and durations are often not indicated.
- (van der Werf, 1997).