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.
Derivatives:
triadic adj. triadically adv.
Etymology: F triade or LL trias triad- f. Gk trias -ados f. treis three
Useful english dictionary. 2012.