On'y adjective Any. [ Obsolete] Chaucer.On'y*cha noun [ New Latin , from Latin onyx , -ychis , onyx, also, a kind of mussel, Greek ..., .... See Onyx .] 1. An ingredient of the Mosaic incense, probably the operculum of some kind of s... Found on http://www.encyclo.co.uk/webster/O/21