noun.
A name of a place, people, or period derived from that of a person.
noun.
A name of a mythical or historical personage from whom the name of a country or people has come or is supposed to have come: thus, Italus, Romulus, Brutus, Heber, the names of imaginary persons invented to account for Italy, Rome, Britain, Hebrew, are mythical eponyms; Bolivar is the historical eponym of Bolivia.
noun.
A name of something, as a part or organ of the body, derived from a person: thus, circle of Willis, fissure of Sylvius, aqueduct of Fallopius, are eponyms.
noun.
The archon eponymus at Athens (see archon); also, one of certain Assyrian functionaries who gave their names to the years during which they held office.