The Collaborative International Dictionary
Eponyme
Eponym \Ep"o*nym\, Eponyme \Ep"o*nyme\, n. [Cf. F. ['e]ponyme. See Eponymous.]
The hypothetical individual who is assumed as the person from whom any race, city, etc., took its name; as, Hellen is an eponym of the Hellenes.
A name, as of a people, country, and the like, derived from that of an individual.
Wiktionary
eponyme
n. (archaic form of eponym English)