/tree"oh/ , n. , pl. trios .
1. a musical composition for three voices or instruments.
2. a company of three singers or players.
3. any group of three persons or things.
4. a subordinate division of a minuet, scherzo, march, etc., usually in a contrasted key and style (perhaps originally written for three instruments or in three parts).
[ 1715-25; tri- TRI- + ( du ) o TWO ]