Polyphonous refers to something that produces multiple sounds or voices simultaneously. There are several synonyms for polyphonous including cacophonous, harmonious, discordant, mellifluous, and euphonious. Cacophonous refers to something that produces a harsh and unpleasant sound, whereas harmonious refers to something that produces a pleasing and well-balanced sound. Discordant refers to something that produces an unpleasant and jarring sound, while mellifluous refers to something that produces a smooth and sweet-sounding voice. Euphonious refers to something that produces a pleasing and melodious sound. All of these synonyms for polyphonous are useful in different contexts and can add depth and nuance to language.