Webster’s Revised Unabridged Dictionary · 1913
Cameo
Cam′e·o, n.; pl. Cameos (#). [It cammeo; akin to F. camée, camaïeu, Sp. camafeo, LL. camaeus, camahutus; of unknown origin.] A carving in relief, esp. one on a small scale used as a jewel for personal adornment, or like.
☞ Most cameos are carved in a material which has layers of different colors, such stones as the onyx and sardonyx, and various kinds of shells, being used.
Cameo conch (Zoöl.), a large, marine, univalve shell, esp. Cassis cameo, C. rua, and allied species, used for cutting cameos. See Quern conch.