Entry 1 sense Webster, 1913 Epithelial /ĕp-ĭth-ĕl'-yəl/ · Ep·i·the·li·al · IPA /ɛpɪθˈɛljəl/ 01 a. Of or pertaining to epithelium; as, epithelial cells; epithelial cancer. 1. Of or pertaining to epithelium; as, epithelial cells; epithelial cancer.