The "Neapolitan disease" is a historical term for syphilis.
During the late 15th century, as syphilis spread rapidly through Europe, various regions attributed the disease to other places. The French, for instance, often called it "the Neapolitan disease," while the Italians frequently referred to it as "the French disease." These names reflected the belief that the disease originated elsewhere and was brought to their region by foreigners. The first documented descriptions of the disease coincide with the Battle of Fornovo in 1495, further cementing its emergence during that period.