Chorus (noun)

1. A group of people who sing together, especially in a musical or theatrical production.
2. A repeated phrase or line in a song or poem.

Origin:

From middle english chor, from old english cór, from latin chorus, from ancient greek χορός (khorós, "dancing place, chorus of singers and dancer.s")

Examples:

1. The chorus of the song was catchy and easy to remember.
2. The chorus sang in harmony.
3. The chorus of the play was made up of actors.
4. The chorus was repeated several times in the song.
5. The chorus of the poem was a refrain.