|1.||an instrumental ensemble consisting of two violins, one viola, and one cello|
|2.||a piece of music written for such a group, usually having the form and commonest features of a sonata|
A musical group that includes two violins, a viola, and a cello. The term also refers to a composition written for these four instruments. Many composers, notably Franz Josef Haydn, Wolfgang Amadeus Mozart, and Ludwig van Beethoven, have written string quartets.