1. a person whose name is or is thought to be the source of the name of something, such as a city, country, or era 2. a name or noun formed in such a way

According to David Crystal in his book Words, Words, Words: “When a name becomes an everyday word in a language, it is called an eponym. It’s interesting, and a little confusing, that eponym can mean both the name and the person after whom the thing was named.