c.1400, from Old French ulcere, from Vulgar Latin ulcerem, from Latin ulcus (genitive ulceris) "ulcer," from PIE *elk-es- "wound" (cf. Greek elkos).
ulcer ul·cer (ŭl'sər)
n.
A lesion of the skin or of a mucous membrane, such as the one lining the stomach or duodenum, that is accompanied by formation of pus and necrosis of surrounding tissue, usually resulting from inflammation or ischemia.
An inflamed open sore on the skin or mucous membrane. An ulcer may form in the inner lining of the stomach or duodenum, interfere with digestion, and cause considerable pain.
Note: It used to be thought that stress was the cause of stomach and duodenal ulcers, but we now know that they are caused by bacteria and can be cured by antibiotics.