define ulcer
A peptic ulcer is a sore on the lining of your stomach or duodenum. Rarely, a peptic ulcer may develop just above your stomach in your esophagus. Doctors call this type of peptic ulcer an esophageal ulcer. Causes of peptic ulcers include. 1  long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen. 2  an infection with the bacteria Helicobacter pylori (H. pylori) 3  rare cancerous and noncancerous tumors in the stomach, duodenum, or pancreasâknown as Zollinger-Ellison syndrome (ZES)