The orifice of any organ or part of the body. spec. (slang) The mouth, the anus, or the female external genital organs.

An opening by which blood issues from the body. Obsolete.

Anatomy and Zoology. A small opening or orifice in a part of the body.

The opening at the end of a tube, passage, drain, etc.; the open end of a trumpet or other wind instrument; (Anatomy) the point at which a blood…

An opening or orifice, a hole or short passage, for the protrusion of an organ, or for the performance of organic functions. In various…

Anatomy and Zoology. An opening or orifice; esp. the entrance to a hollow organ. Frequently in compounds with postmodifying classical…

Anatomy and Zoology. A small opening in an animal body; an aperture, orifice, pore (as of a lymphatic or other vessel, an air-tube, etc.).

Medicine and Surgery. A slit-like opening in a part of the body, esp. that between the thickened leaflets of a stenotic heart valve. Also: a small…

Anatomy. The upper opening into a cavity of the body; used originally of the pelvis and later of the thorax (both as cavities of the skeleton)…

Anatomy and Zoology. The opening of or entrance into a cavity or channel (frequently with distinguishing scientific Latin word or phrase denoting…

More fully external os: the opening of the cervix into the vagina; the os uteri or os externum. Also (in full internal os): the constriction of the…

Anatomy. An opening or foramen. Also attributive, as hiatus hernia n. a hernia in which an organ, esp. the stomach, protrudes through the œsophageal…