/ ˈtraɪæd; NAmE / noun
1.
( formal ) a group of three related people or things
2.
(also Triad ) a Chinese secret organization involved in criminal activity
••
WORD ORIGIN
mid 16th cent.: from French triade , or via late Latin from Greek trias , triad- , from treis three. Sense 2 is a translation of Chinese San Ho Hui , literally three unite society, i.e. triple union society , said to mean the union of Heaven, Earth, and Man .