The Collaborative International Dictionary of English v.0.48:

Bubo \Bu"bo\ (b[=u]"b[-o]), n.; pl. Buboes (-b[-o]z). [LL.
   bubo the groin, a swelling in the groin, Gr. boubw`n.] (Med.)
   An inflammation, with enlargement, of a lymphatic gland, esp.
   in the groin, as in syphilis.
   [1913 Webster]