(1):

(n.) Composition in mutually related, equally important parts which share the melody among them; contrapuntal composition; - opposed to homophony, in which the melody is given to one part only, the others filling out the harmony. See Counterpoint.

(2):

(n.) Plurality of sounds and articulations expressed by the same vocal sign.

(3):

(n.) Multiplicity of sounds, as in the reverberations of an echo.