Source : Webster's Revised Unabridged Dictionary (1913)

Enteron \En"te*ron\, n. [NL., fr. Gr. ? an intestine, fr.
   'ento`s within.] (Anat.)
   The whole alimentary, or enteric, canal.

Source : WordNet®

enteron
     n : the alimentary canal (especially of an embryo or a
         coelenterate)
     [also: {entera} (pl)]