Princeton's WordNet

1. four, 4, IV, tetrad, quatern, quaternion, quaternary, quaternity, quartet, quadruplet, foursome, Little Joe(noun)

   the cardinal number that is the sum of three and one

2. quartet, quartette(noun)

   four performers or singers who perform together

3. quartet, quartette, quadruplet, quadruple(noun)

   a set of four similar things considered as a unit

4. quartet, quartette, foursome(noun)

   four people considered as a unit

   "he joined a barbershop quartet"; "the foursome teed off before 9 a.m."

5. quartet, quartette(noun)

   a musical composition for four performers

Wiktionary

1. quartet(Noun)

   A music composition in four parts, each performed by a single voice or instrument.

   A string quartet.

2. quartet(Noun)

   The set of four musicians who perform a piece of music together in four parts.

   A quartet of violinists.

3. quartet(Noun)

   A group of four.

Origin: quartetto.

Webster Dictionary

1. Quartet(noun)

   alt. of Quartette

• kwartet, viertalAfrikaans
• مَجْموعَةٌ من أرْبَعَة عازِفينArabic
• квартетBulgarian
• quartetoPortuguese (BR)
• kvartetoCzech
• das QuartettGerman
• kvartetDanish
• κουαρτέτο (μουσικό σχήμα με τέσσερις μουσικούς)Greek
• cuartetoSpanish
• kvartettEstonian
• گروه چهار نفریFarsi
• kvartettiFinnish
• quatuorFrench
• רְבִיעִייָהHebrew
• चार का गुटHindi
• kvartetCroatian
• (zenei) négyesHungarian
• kuartetIndonesian
• kvartettIcelandic
• quartettoItalian
• ４重奏Japanese
• 4중창Korean
• kvartetasLithuanian
• kvartetsLatvian
• kuartetMalay
• kwartetDutch
• kvartettNorwegian
• kwartetPolish
• گروه چهار نفریPersian
• څلور كسيزه ډله په تېره دسندر غاړو يا لوبغاړو: دنظم يا شعر هغه ټوټه چې څلور برخې يا څلور اّوازه ولري او دڅلور كسو له خوا ويل كيږيPashto
• quartetoPortuguese
• cvar­tetRomanian
• квартетRussian
• kvartetoSlovak
• kvartetSlovenian
• kvartetSerbian
• kvartettSwedish
• วงดนตรีมีผู้เล่นสี่คนThai
• dörtlü, kuartetTurkish
• 四重唱，四重奏Chinese (Trad.)
• квартетUkrainian
• کسی ساز کو بجانے والا چار گلوکاروں کا گروہUrdu
• tứ ca; nhóm tứ tấuVietnamese
• 四重唱，四重奏Chinese (Simp.)