(n) an aperture or hole that opens into a bodily cavity, Syn. opening, porta, Example:the orifice into the aorta from the lower left chamber of the heart
The Collaborative International Dictionary of English (GCIDE) v.0.53 Collaborative International Dictionary (GCIDE)
n. [ F., from L. orificium; os, oris, a mouth + facere to make. See Oral, and Fact. ] A mouth or aperture, as of a tube, pipe, etc.; an opening; as, the orifice of an artery or vein; the orifice of a wound. Shak. [ 1913 Webster ]
Etna was bored through the top with a monstrous orifice. Addison. [ 1913 Webster ]