Etymology: (1350–1400; ME < MF trei(s) < L trēsthree)
Definition of 'trey'
Princeton's WordNet
1. (noun)three, 3, III, trio, threesome, tierce, leash, troika, triad, trine, trinity, ternary, ternion, triplet, tercet, terzetto, trey, deuce-ace the cardinalnumber that is the sum of one and one and one