Eponym
An
eponym can be either an item which provides a
name-source for a particular place, tribe, era, discovery, or other item to be named, or it can also be an item which acts as a
name-recipient. For example, Léon Theremin is the eponym of the theremin, an electronic musical instrument; or, the medical term
Parkinson's disease is a medical eponym, named after the English physician, James Parkinson. Similarly, the term
eponymous has parallel meanings when employed as an adjective. An etiological myth can be a "reverse eponym" in the sense that a legendary character is invented in order to explain a term, such as the nymph Pirene, who according to myth was turned into Pirene's Fountain.