A symphony is an extended musical composition in Western classical music, most often written by composers for orchestra. Although the term has had many meanings from its origins in the ancient Greek era, by the late 18th century the word had taken on the meaning common today: a work usually consisting of multiple distinct sections or movements, often four, with the first movement in sonata form. Symphonies are scored for string (violin, viola, cello and double bass), brass, woodwind, and percussion instruments which altogether number about 30–100 musicians. Symphonies are notated in a musical score, which contains all the instrument parts. Orchestral musicians play from parts which contain just the notated music for their instrument. A small number of symphonies also contain vocal parts (e.g., Beethovens Ninth Symphony). The word symphony is derived from Greek s?µf???a (symphonia), meaning "agreement or concord of sound", "concert of vocal or instrumental music", from s?µf???? (symphonos), "harmonious". The word referred to an astonishing variety of different things, before ultimately settling on its current meaning designating a musical form. In late Greek and medieval theory, the word was used for consonance, as opposed to d?af???a (diaphonia), which was the word for dissonance. In the Middle Ages and later, the Latin form symphonia was used to describe various instruments, especially those capable of producing more than one sound simultaneously. Isidore of Seville was the first to use the word symphonia as the name of a two-headed drum, and from c. 1155 to 1377 the French form symphonie was the name of the organistrum or hurdy-gurdy. In late medieval England, symphony was used in both of these senses, whereas by the 16th century it was equated with the dulcimer. In German, Symphonie was a generic term for spinets and virginals from the late 16th century to the 18th century.