EPONYM
eponym
(noun) the name derived from a person (real or imaginary); “Down’s syndrome is an eponym for the English physician John Down”
eponym
(noun) the person for whom something is named; “Constantine I is the eponym for Constantinople”
Source: WordNet® 3.1
Etymology
Noun
eponym (plural eponyms)
A real or fictitious person's name that has given rise to the name of a particular item.
A word formed from a real or fictive person’s name.
Synonym: namesake
(loosely, nonstandard, by extension) A word formed from a real or fictive place or thing.
Synonym: toponym
Source: Wiktionary
Ep"o*nym, Ep"o*nyme, n. Etym: [Cf. F. Ă©ponyme. See Eponymous.]
1. 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.
2. A name, as of a people, country, and the like, derived from that
of an individual.
Source: Webster’s Unabridged Dictionary 1913 Edition