ULCER

term applied to an open sore formed by a gradual breaking down of ti ue in skin or mucous membrane; chief varieties are simple, due to gradual death of the ti ue cells through lack of nutrition, or to traumatism; specific, due to the action of a specific microorganism, e.g. of tuberculosis or syphilis; malignant, due to the replacement of the skin or mucous membrane by a malignant growth, e.g. epithelioma.