corium (ˈkɔːrɪəm) n, pl -ria (-rɪə) 1. (Anatomy) Also called: derma or dermis the deep inner layer of the skin, beneath the epidermis, containing connective tissue, blood vessels, and fat 2. (Zoology) entomol the leathery basal part of the forewing of hemipterous insects [C19: from Latin: rind, skin, leather]