Source : Webster's Revised Unabridged Dictionary (1913)

Quartet \Quar*tet"\, Quartette \Quar*tette"\, n. [It. quartetto,
   dim. of quarto the fourth, a fourth part, fr. L. quartus the
   fourth. See {Quart}.]
   1. (Mus.)
      (a) A composition in four parts, each performed by a
          single voice or instrument.
      (b) The set of four person who perform a piece of music in
          four parts.

   2. (Poet.) A stanza of four lines.

Source : WordNet®

quartet
     n 1: the cardinal number that is the sum of three and one [syn: {four},
           {4}, {IV}, {tetrad}, {quatern}, {quaternion}, {quaternary},
           {quaternity}, {quadruplet}, {foursome}, {Little Joe}]
     2: four performers or singers who perform together [syn: {quartette}]
     3: a set of four similar things considered as a unit [syn: {quartette},
         {quadruplet}]
     4: four people considered as a unit; "he joined a barbershop
        quartet"; "the foursome teed off before 9 a.m." [syn: {quartette},
         {foursome}]
     5: a musical composition for four performers [syn: {quartette}]