ulcer /ul″sər/ [L, ulcus, a sore] , a circumscribed, craterlike lesion of the skin or mucous membrane resulting from necrosis that accompanies some inflammatory, infectious, or malignant processes. An ulcer may be shallow, involving only the epidermis, as in pemphigus, or deep, as in a rodent ulcer. Kinds include peptic ulcer, pressure ulcer, serpent ulcer. −ulcerative, adj., −ulcerate, v.
