Trey

google

ref

late Middle English: from Old French trei ‘three’, from Latin tres .

wiktionary

ref

From Middle English treye, from Anglo-Norman trei or treis, from Old French treis(“three”). Doublet of three.

etymonline

ref

trey (n.)

late 14c., "card, die, or domino with three spots," from Anglo-French, Old French treis (Modern French trois), oblique case of treie "three," from Latin tria (neuter) "three" (see three). In slang use for "three (of anything)" from 1887.