noun (n)

• an aperture or hole that opens into a bodily cavity(noun.body)

  Example:
  The orifice into the aorta from the lower left chamber of the heart.
  

  Synonym:
  opening, porta
  

  source: wordnet30
• 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.(noun)

  source: webster1913