quartet

(noun) the cardinal number that is the sum of three and one. Synonyms: four, 4, IV, tetrad, quatern, quaternion, quaternary, quaternity, quadruplet, foursome, Little Joe.

(noun) four performers or singers who perform together. Synonyms: quartette.

(noun) a set of four similar things considered as a unit. Synonyms: quartette, quadruplet, quadruple.

(noun) four people considered as a unit. Synonyms: quartette, foursome. Examples: "He joined a barbershop quartet." "The foursome teed off before 9 a.m.."

(noun) a musical composition for four performers. Synonyms: quartette.