[ 'trʌɪad ]
1》 a group or set of three connected people or things.
↘a chord of three musical notes, consisting of a given note with the third and fifth above it.
↘a Welsh form of literary composition with an arrangement of subjects or statements in groups of three.
2》 a Chinese secret society involved in organized crime.
↘a member of such a society.
C16: from Fr. ~e , or via late L. from Gk trias , ~- , from treis 'three'.