Nummulitic, composed of, or containing a fossil of a flattened form, resembling a small coin, and common in the early tertiary period.
Obsidian, a kind of glass produced by volcanoes.
Occipital, pertaining to the back part of the head.
Ochreous, consisting of fine clay, containing iron.
Olecranon, the large process at the extremity of the larger bone of the fore-arm.
Onusprobandi, the burden of proof.
Orbit, the cavity in which the eye is located; the path described by a heavenly body in its periodical revolution.
Osar, a low ridge of stone or gravel formed by glaciers.
Oscillation, the act of moving backward and forward.
Osseous, composed of bone.