quartet

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Music A composition for four voices or four instruments.
2. n. Music A group of four singers or four instrumentalists.
3. n. A group of four.

Century Dictionary and Cyclopedia

1. n. In music: A composition or movement for four solo parts, either vocal or instrumental, usually without accompaniment. Specifically, an instrumental work, usually for four stringed instruments, written in sonata form, and planned like a small symphony; a string-quartet. The quartet is the highest variety of chamber-music. It first reached its full development at the end of the eighteenth century.
2. n. A company of four singers or players who perform quartets. A mixed vocal quartet properly consists of a soprano (treble), an alto, a tenor, and a bass. A string-quartet consists of two violins, a viola, and a violoncello.
3. n. In an orchestra the stringed instruments collectively, and in oratorio music the principal vocal soloists, are sometimes loosely called the quartet.
4. n. A stanza of four lines.
5. n. Same as quadruplet.
6. n. The performers of such a composition, whether vocal or instrumental.
7. n. In embryology, a group of four cleavage-cells considered as a unit, either because they arise at the same time, or because they have a similar origin or prospective function.

Wiktionary

1. n. music A music composition in four parts, each performed by a single voice or instrument.
2. n. music The set of four musicians who perform a piece of music together in four parts.
3. n. A group of four.

GNU Webster's 1913

1. n. A composition in four parts, each performed by a single voice or instrument.
2. n. The set of four person who perform a piece of music in four parts.
3. n. (Poet.) A stanza of four lines.

WordNet 3.0

1. n. four performers or singers who perform together
2. n. four people considered as a unit
3. n. the cardinal number that is the sum of three and one
4. n. a set of four similar things considered as a unit
5. n. a musical composition for four performers