Cardia

from WordNet (r) 3.0 (2006)

cardia
    n 1: the opening into the stomach and that part of the stomach
         connected to the esophagus

from The Collaborative International Dictionary of English v.0.48

Cardia \Car"di*a\, n. [NL., fr. Gr. ? heart, or upper orifice of
   the stomach.] (Anat.)
   (a) The heart.
   (b) The anterior or cardiac orifice of the stomach, where the
       esophagus enters it.
       [1913 Webster]