Meaning

noun a chalcedony with alternating black and white bands; used in making cameos

originFrom Middle English onix (c. 1300), earlier oniche (c. 1250), from Old French oniche or onix, from Latin onyx, from Ancient Greek ὄνυξ (ónux, “onyx”). Doublet of unguis.

Etymology from Wiktionary, CC BY-SA 3.0