How do you spell Trio

Available Definitions:
1)  n. - Three, considered collectively; three in company or acting together; a set of three; three united.
2)  n. - A composition for three parts or three instruments.
3)  n. - 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.