Canker sore: A common small, frequently painful and sensitive crater in the lining of the mouth. Also known as aphthous ulcer. Sores typically last for 10 to 14 days and generally heal without scarring.
Canker sore: A common small, frequently painful and sensitive crater in the lining of the mouth. Also known as aphthous ulcer. Sores typically last for 10 to 14 days and generally heal without scarring.
