aphtha

(medicine) White, painful oral ulcer of unknown cause.

(aphthous stomatitis), 1. a small ulcer on the mucous membrane. -hae n.pl 2. vesicles that undergo subsequent ulceration and are surrounded by a raised erythematous area.

A minute painful ulcer on a mucous membrane of the mouth, often covered by a gray or white exudate.

Pl. aphthae [L.] see foot-and-mouth disease.