1. An old name for paleontology.
2. An old name for mineralogy and geology.
ORYX
O"ryx, n. Etym: [NL., from Gr. (Zoöl.)
Defn: A genus of African antelopes which includes the gemsbok, the leucoryx, the bisa antelope (O. beisa), and the beatrix antelope (O. beatrix) of Arabia.
ORYZA
O*ry"za, n. Etym: [L., rice, Gr. Rice.] (Bot.)
Defn: A genus of grasses including the rice plant; rice.
OS
Os, n.; pl. Ossa. Etym: [L.]
Defn: A bone.
OS
Os, n.; pl. Ora. Etym: [L.]
Defn: A mouth; an opening; an entrance.