Chorus

Broadly speaking, a chorus is any substantial group of performers in a play, revue, musical or opera who act more or less as one. It can also mean a work, or section of a work, performed by a chorus. Today, it is most usually used as a synonym for choir to mean a group of singers who all sing together or a piece sung by such a group, but it can also mean a group of dancers, and in Greek drama it meant a group of actors.

In colloquial usage, chorus is used to mean the refrain of a song.