Elephantiasis
/ˌelɪfənˈtaɪəsɪs/
Definition 1 of 1
Pro Tip 1/3Caused by Parasites
Most cases are due to parasitic infection; remember, it's not due to the animal elephant. 
Travelers visiting endemic areas may risk contracting elephantiasis if bitten by infected mosquitoes.
Pro Tip 2/3Medical Specificity
Use 'elephantiasis' to refer to severe lymphatic swelling, distinct from ordinary swelling or edema. 
After years of untreated infection, he developed elephantiasis, not just simple swelling.
Pro Tip 3/3Severity and Size
Understand that the term implies an extreme increase in size and usually indicates a serious condition. 
The disease progressed to the point of elephantiasis, with her leg becoming massively enlarged.