Sub·e`so·phag'e·al adjective (Zoology) Situated beneath the esophagus. [ Written also subœsophageal .] Subesophageal ganglion (Zoology) , a large special ganglion situated beneath the esophagus of arthropods, annelids, and some other invertebrates. Found on http://www.encyclo.co.uk/webster/S/222