composition written in three parts but usually played by four people (the continuo part being "realized" by two musicians). The trio sonata was the most important instrumental form of the baroque.

A Baroque sonata for two treble instruments and continuo, generally requiring four performers.

A chamber music form for two featured instruments and continuo accompaniment; especially popular in the 17th and 18th centuries.

though the term implies three (trio), a trio sonata normally employs 4 performers--two melodic parts, and two instruments (a melodic one and a chordal one) on the continuo part. There are, however, three separate parts in the score.

Baroque chamber sonata type written in three parts: two melody lines and the basso continuo; requires a total of four players to perform.

A type of Baroque chamber music written in three parts (two upper voices plus a thoroughbass part). A trio sonata is normally performed by four instruments, e.g., two violins in the upper voices, a violoncello or bassoon to play the bass line, and an instrument such as a harpsichord or lute to provide the realization of the thoroughbass accompaniment. For cataloging and classification purposes, a trio sonata is considered a trio. (Thorin)

A baroque sonata for three main instruments plus the continuo chord instruments.

Sonata for two main instruments, always accompanied by the continuo.

The trio sonata is a musical form which was particularly popular around the 17th century and the 18th century.