part song

a song with parts for several voices, especially one meant to be sung without accompaniment.

Origin of part song

First recorded in 1590–1600

part singing, noun

A part-song is a composition for two or more voices, (usually four) to be sung a capella.

Music Notation and Terminology |Karl W. Gehrkens
Part-song was simplified, and Johan Walther compiled a hymnal of religious songs in the vernacular for from four to six voices.

The Story of the Hymns and Tunes |Theron Brown and Hezekiah Butterworth
The sanction of the cardinals was given—and part-song harmony became permanently one of the angel voices of the Christian church.

The Story of the Hymns and Tunes |Theron Brown and Hezekiah Butterworth
Suddenly, from a grove behind us, came the sound of children's voices singing an old German part-song.

A Camera Actress in the Wilds of Togoland |Meg Gehrts

Let us take six gentlemen met together to learn the old thirteenth-century part-song, the round entitled ‘Sumer is icumen in.’

English Costume |Dion Clayton Calthrop

part song

a song composed in harmonized parts

(in more technical usage) a piece of homophonic choral music in which the topmost part carries the melody