"Aphthous affectations" and "aphthous ulcerations" of the mouth are mentioned several times in the treatise "Of the Epidemics" (part of the
Hippocratic corpus, in the 4th century BCE), although it seems likely that this was oral ulceration as a manifestation of some infectious disease, since they are described as occurring in
epidemic-like patterns, with concurrent symptoms such as fever. Aphthous stomatitis was once thought to be a form of recurrent herpes simplex virus infection, and some clinicians still refer to the condition as "herpes" despite this cause having been disproven. The informal term "canker sore" is sometimes used, mainly in North America, either to describe this condition generally, or to refer to the individual ulcers of this condition, or mouth ulcers of any cause unrelated to this condition. The origin of the word "canker" is thought to have been influenced by Latin, Old English, Middle English and Old North French. In Latin,
cancer translates to "malignant tumor" or literally "crab" (related to the likening of sectioned tumors to the limbs of a crab). The closely related word in Middle English and Old North French,
chancre, now more usually applied to
syphilis, is also thought to be involved. The lesions of several other oral conditions are sometimes described as aphthae, including
Bednar's aphthae (infected, traumatic ulcers on the hard palate in infants),
oral candidiasis, and
foot-and-mouth disease. When used without qualification,
aphthae commonly refers to lesions of recurrent aphthous stomatitis. Since the word aphtha is often taken to be synonymous with ulcer, it has been suggested that the term "aphthous ulcer" is redundant,