the.com/eponym

means A person (or sometimes place or thing) whose name has become the name for something else — a word, an era, a disease, a unit of measure.

from From Greek 'eponymos,' meaning 'giving one's name to' — built from 'epi' (upon) plus 'onoma' (name). The Greeks used it for the officials and heroes after whom years, cities, or institutions were named; the word simply migrated from the person doing the naming-after to any word born the same way.