sin·fo·ni·a / ˌsinfəˈnēə/ • n. Mus. a symphony. ∎  (in the 17th and 18th centuries) an orchestral piece used as an introduction, interlude, or postlude to an opera, oratorio, cantata, or suite.

sinfonia (It.). Symphony.
1. Symphony.

2. Bach's term for his 3-part inventions.

3. Name given in Baroque period to orch. piece which served as 3-movt. introduction to opera, suite, or cantata, i.e. an early form of ov. Operatic sinfonia standardized c.1690 by A. Scarlatti into so-called ‘Italian overture’.

4. In 20th cent., often means a chamber orch., e.g. Northern Sinfonia, English Sinfonia.