aphtha /af″thē/ [Gk, aphtha, eruption] , a small, shallow, painful ulceration that usually affects the oral mucosa but not underlying bone. Aphthae occasionally may affect other body tissues, including those of the GI tract and the external genitals. They do not appear to be infectious, contagious, or sexually transmitted. See also aphthous stomatitis, foot-and-mouth disease. −aphthous, adj.
