ChorusChorus: when referring to performers, a chorus is a vocal ensemble. Choruses vary greatly in size, from chamber-like groups of eight to twelve to a hundred or more singers. The performance of choral music most commonly requires sopranos, altos, tenors, and basses (see Chapter 2: Musical Instruments and Ensembles, section on Human Voice as Instrument) but there is also important choral literature for women, men, children, and boys. The other use of the word chorus denotes a section of a musical work, either the refrain of a song or, in a jazz composition, the harmonic/melodic theme and its varied repetitions.