Entry 1 sense Webster, 1913 Adenoma /(ăd`ē̇*nō"mȧ)/ · Ad·e·no·ma · IPA /ædəˈnoʊmə/ 01 n. A benign tumor of epithelial tissue with a glandlike structure. pl. -mata ((#)) 1. A benign tumor of epithelial tissue with a glandlike structure.(Med.)