Entry 1 sense Webster, 1913 Duodenal /do͞o'-əd-ēn'-əl/ · Du·o·de·nal · IPA /ˌduəˈdinəl/ 01 a. Of or pertaining to the duodenum; as, duodenal digestion. 1. Of or pertaining to the duodenum; as, duodenal digestion.