Webster’s Revised Unabridged Dictionary · 1913
Onycha
On′y·cha (ŏn′ĭ·kȧ), n. [NL., from L. onyx, -ychis, onyx, also, a kind of mussel, Gr. ὄνυξ, -υχος. See Onyx.]
1. An ingredient of the Mosaic incense, probably the operculum of some kind of strombus. Ex. xxx. 34.
2. The precious stone called onyx. [R.]