Trio is ‘trio’, from Italian trio, from tri- patterned on duo. and means:
1 a: a musical composition for three voice parts of three instruments b: the secondary or episodic division of a minuet or scherzo (as in a sonata or symphony) or of a march or of various dance forms, usu. contrasted in key and in a quieter style than the primary division c: a performance of such a composition d: a dance by three people.
2: a group or set of three as a: the performers of a musical or dance trio b: three playing cards of the same rank c: a male and two female domestic animals (as poultry) froming a breeding or exhibition group”