aphtha

noun

aph·​tha ˈaf-thə, ˈap-thə 

variants also aptha

ˈap- 

plural aphthae also apthae -ˌthē 

1

: a speck, flake, or blister on the mucous membranes (as in the mouth or gastrointestinal tract or on the lips) characteristic of some diseases (as thrush)

2

: one of the vesicles filled with clear serous fluid that occur in the mouth, on the udder, and in the spaces between the digits of cloven-footed animals in some diseases

—usually used in plural

3

: a disease (as foot-and-mouth disease) characterized by aphthae

aphthic

-thik 

adjective