(music) A group of four musicians who perform classical music together. / (music) A musical composition in four parts, each performed by a single voice or instrument.

plural of quartet

(music) A group of four musicians who sing barbershop music. Usually contains high and lead tenors, baritone and bass.

(music) A group of four musicians playing string instruments, usually two violins, a viola and a cello. / (music) A musical composition for such a group.

plural of barbershop quartet

plural of string quartet