Synonyms for Trey:

n.

three (noun)
trio.
trey (noun)
tercet, trine, troika, tierce, three, trio, ternion, terzetto, trinity, leash, ternary, 3, triplet, iii, deuce-ace, triad.
triad (noun)
three.
trio/triple (noun)
ternion, trinity, leash, triad, troika, triplet, trine.

Other synonyms:

III
iii.