In music, a sinfonia can be one of three things:

1) In the very late Renaissance and early Baroque, a sinfonia was an alternate name for a canzona, fantasia or ricercar. These were almost always instrumental forms. Later in the Baroque period it was more likely to be a type of sonata, especially a trio sonata or one for larger ensemble. Three-part inventions were also known as sinfonias (though contemporary publishers are increasingly referring the them as simply "Three-Part Inventions"). Occasionally, later in the Baroque, the word was used to designate an instrumental prelude, as in definition 2).

2) In larger vocal-instrumental forms of the 17th and 18th centuries, for example operas and oratorios, a sinfonia was generally an instrumental prelude, interlude or postlude, providing contrast with adjacent sections. A famous example is the beginning of Handel's Messiah.

A special and very important case of this, in the 18th century, was the three-movement sinfonia which developed as an overture to Italian opera. Most of the time these pieces were in D major (for maximizing open-string resonance on string instruments). This type of sinfonia was the most important predecessor to the symphony. Most of Mozart's earliest symphonies--those he wrote up to the age of about 15--are imitations of the Italian sinfonia. Other good examples of the sinfonia in this sense are the numerous three-movement opera overtures by Alessandro Scarlatti. As the 18th century progressed, the word "overture" was used more and more as a title for these pieces, with "sinfonia" being used for independent concert pieces in similar style. The overture developed rapidly into a one-movement form, though retaining many of the features of the original sinfonia, for instance a loud, triadic, motto-type leading motif, a reprise preceded with minimal thematic development, and overall mood of expectation rather than resolution.

3) A sinfonia is an occasional alternate name for a symphony. This is the usage most common for music written in the 20th and 21st centuries. Usually, but not always, the title "sinfonia" is used when the work is intended to be lighter, shorter, or more Italianate in character than a symphony (which had a more Germanic pedigree).

The word is derived from Greek Symphonia, which means "sounding together."

Sources

• Manfred Bukofzer, Music in the Baroque Era. New York, W.W. Norton & Co., 1947. ISBN 0393097455
• The New Harvard Dictionary of Music, ed. Don Randel. Cambridge, Massachusetts, Harvard University Press, 1986. ISBN 0674615255
• Article Sinfonia, in The New Grove Dictionary of Music and Musicians, ed. Stanley Sadie. 20 vol. London, Macmillan Publishers Ltd., 1980. ISBN 1561591742