RhymeZone: aphtha definitions

Definitions of aphtha:

noun: (pathology) Candidiasis, oral thrush, thrush (fungal infection of the mucous membranes of the mouth caused by any species of yeast from the genus Candida).
noun: An oral ulcer, disregarding the cause.
noun: (veterinary medicine) Foot-and-mouth disease.

(Definitions from Wiktionary)