n pl but sing or pl in constr :  an infectious contagious tropical disease that is caused by a spirochete of the genus Treponema (T. pertenue) and that is characterized by a primary ulcerating lesion on the skin followed by a secondary stage in which ulcers develop all over the body and by a third stage in which the bones are involved - called also frambesia , pian  .
 
 
 
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