Definition · Plain-language
Eponym
An eponym is a word or name derived from the name of a person — such as sandwich, boycott or diesel — or the person after whom something is named.
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Words named after people
The word eponym comes from Greek roots meaning "named upon" or "named after". An eponym is most often a common word that began as someone’s name and then entered the general vocabulary. Many everyday English words are eponyms: a cardigan recalls the Earl of Cardigan, to boycott honours the land agent Charles Boycott who was shunned by his community, and saxophone preserves its inventor Adolphe Sax. Once an eponym is fully absorbed, it is usually written in lower case — sandwich, diesel, watt — even though the original name was capitalised, a sign that the word has become independent of the person.
Eponyms in science and medicine
Science, medicine and measurement are full of eponyms that honour discoverers and inventors. Units of measurement such as the watt (James Watt), the volt (Alessandro Volta), the newton (Isaac Newton) and the hertz (Heinrich Hertz) are eponymous, as are diseases and conditions like Parkinson’s and Alzheimer’s. Mathematical and scientific results — Boolean logic, the Fahrenheit scale, pasteurisation — also carry their originators’ names. Such eponyms credit individual contribution, though in recent decades some fields have moved toward descriptive names instead, partly because an eponym tells you nothing about what the thing actually is.
Two directions of the word
Eponym is used in two related ways. In the first, the eponym is the derived word — sandwich is an eponym of the Earl of Sandwich. In the second, the eponym is the person who gives their name — the Earl is the eponym of the sandwich, and Rome’s legendary founder Romulus is the eponym of Rome. Both uses are correct, and context makes clear which is meant. A closely related idea is the eponymous adjective in titles: an album is eponymous when it shares its name with the band, and a character is eponymous when the work is named after them, as Hamlet is in Hamlet.
Key facts
At a glance
- Definition: a word or name derived from the name of a person
- Origin: Greek epi (upon) + onoma (name) — "named upon"
- Examples: sandwich, boycott, diesel, cardigan, saxophone
- In science: units such as watt, volt, newton and hertz
- Two senses: the derived word, or the person it is named after
- Spelling: fully absorbed eponyms are usually lower case
Common misconceptions
What people often get wrong
Often heard: An eponym only means the new word, never the person.
Actually: Eponym works in both directions. It can mean the derived word (sandwich) or the person who gives their name (the Earl of Sandwich). Context shows which sense is intended.
Often heard: Eponyms are always written with a capital letter.
Actually: Once an eponym is fully absorbed into everyday language it is usually lower case — sandwich, diesel, watt, boycott — even though it began as a capitalised personal name.
Often heard: An eponym is the same as a portmanteau.
Actually: They are different. An eponym derives from a person’s name; a portmanteau blends two existing words (brunch from breakfast and lunch). The source is what distinguishes them.
Going deeper
