The Collaborative International Dictionary of English v.0.48:

Orifice \Or"i*fice\, 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] Oriflamb

WordNet (r) 3.0 (2006):

orifice
    n 1: an aperture or hole that opens into a bodily cavity; "the
         orifice into the aorta from the lower left chamber of the
         heart" [syn: orifice, opening, porta]