pylorus

from WordNet (r) 3.0 (2006)

pylorus
    n 1: a small circular opening between the stomach and the
         duodenum

from The Collaborative International Dictionary of English v.0.48

Pylorus \Py*lo"rus\, n.; pl. {Pylori}. [L., fr. Gr. ? pylorus,
   gate keeper; ? a gate + ? watcher, guardian.] (Anat.)
   (a) The opening from the stomach into the intestine.
   (b) A posterior division of the stomach in some
       invertebrates.
       [1913 Webster]