'A kind of garment mentioned in the Old Testament, which differed according to its use by the high-priest, by other persons present at religious services, or as the object of idolatrous worship' (Catholic Encyclopedia ad loc., with more on these three areas: web address 1). See also Jewish Encyclopedia s.v., web address 2.
cf. Hesychius epsilon7535 (where Latte cites 1 Kingdoms 2.18 LXX exempli gratia) and epsilon7536.