Entry 1 sense Webster, 1913 Gastrointestinal /găsˌ-trō-ĭn-tĕs'-tən-əl/ · Gas·tro·in·tes·ti·nal · IPA /ˌɡæstɹoʊɪnˈtɛstɪnəl/ 01 a. Of or pertaining to the stomach and intestines; gastroenteric. 1. Of or pertaining to the stomach and intestines; gastroenteric.(Anat. & Med.)