Standard layout of a modern symphony orchestra.—© Merriam-Webster Inc.

Instrumental ensemble of varying size and composition. Today the term orchestra usually refers to the traditional large Western ensemble of bowed stringed instruments with brass, woodwind, and percussion instruments, with several players to each string part. The development of the orchestra coincides with the early history of opera. A major antecedent of the modern orchestra was that of the mid-17th-century French court, especially as employed by Jean-Baptiste Lully; it was dominated by 24 bowed strings but also often included woodwind instruments. Trumpets, horns, and timpani were often added in the early 18th century and were standard by the time of Franz Joseph Haydn. During the 19th century there was a considerable expansion, particularly in the number and variety of wind and percussion instruments; some works called for well over 100 musicians. The symphony orchestra changed little in the 20th century. See also orchestration.

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