onyx Meaning, Definition & Usage

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

WordNet

O"nyx noun
Etymology
L., fr. Gr. a claw, finger nail, a veined gem. See Nail, and cf. Onycha.
Definitions
  1. (Min.) Chalcedony in parallel layers of different shades of color. It is used for making cameos, the figure being cut in one layer with the next as a ground.

Webster 1913