eponym

A person who gave or supposedly gave their name to a people, place, institution, etc.

The Greeks and Romans tended to credit nearly every location and ethnicity to a legendary eponym, Hellas to Hellen, Rome to Romulus, Egypt to Aegyptus, etc.

Similar to the Greek eponymous archons and Roman consuls, the names of the annually appointed Assyrian limus were used for their years in office and they are accordingly also known as eponyms.

Something that is named after a person.

A name taken from a person, a namesake toponym, term, etc.

Alexandria is an eponym, taken from its founder Alexander the Great.

[Mesmer] lives on today as the root of the eponym mesmerize.

A name or term derived from any proper noun, inclusive of places, brands, etc.

"Tangerine" is an eponym in reference to Tangier... The unflattering eponym "shanghai" derived from the behavior of American shippers, not the Chinese themselves...

Synonym of epitome, a person taken as a symbol or quintessential representative of some trait, school, etc.

Rockefeller became the very eponym of wealth.