Meaning of TRIAD in English

n. 1 a group of three (esp. notes in a chord). 2 the number three. 3 a Chinese secret society, usu. criminal. 4 a Welsh form of literary composition with an arrangement in groups of three. triadic adj. triadically adv.

[ F triade or LL trias triad- f. Gk trias -ados f. treis three ]

Concise Oxford English dictionary.      Краткий оксфордский словарь английского языка.