a musical composition for three voices or instruments.

a company of three singers or players.

any group of three persons or things.

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).

noun

leash , ternion , threesome , trey , triad , triangle , trilogy , trine , trinity , triple , triplet , triplicate , triptych , triumvirate , triune , troika , three , triunity