(Tıp, İlaç) An aphthous ulcer or canker sore is a type of mouth ulcer which presents as a painful open sore inside the mouth, caused by a break in the mucous membrane. The condition is also known as aphthous stomatitis, and alternatively as "Sutton's Disease," especially in the case of multiple or recurring ulcers
a blister on the mucous membranes of the lips or mouth or gastrointestinal tract