Trio

Part of speech: noun (n.)

1. Three, considered collectively; three in company or acting together; a set of three; three united. The trio were well accustomed to act together, and were linked to each other by ties of mutual interest. Dickens.

2. A composition for three parts or three instruments.

3. The secondary, or episodical, movement of a minuet or scherzo, as in a sonata or symphony, or of a march, or of various dance forms; -- not limited to three parts or instruments.