What is parts of a song or hymn recurring at intervals, as at the end of stanzas; also, a company of singers who join with the singer or choir in singer or choir in singing such parts called?

chorus — (Mus.) Parts of a song or hymn recurring at intervals, as at the end of stanzas; also, a company of singers who join with the singer or choir in singer or choir in singing such parts. (Webster's 1913.)