A word derived from a person’s name, such as “sandwich,” is called an eponym. The term can also refer to the person, place, or figure whose name supplies the word.
“Sandwich” is traditionally associated with John Montagu, the 4th Earl of Sandwich, an 18th-century English statesman. According to a popular story, he requested meat served between pieces of bread so he could continue working or playing cards without using a knife and fork. Whether the famous anecdote is fully accurate, the food and its name became firmly associated with him.
Other familiar eponyms include boycott, named after the land agent Charles Boycott, and diesel, named after inventor Rudolf Diesel. Some eponyms begin as people’s names and later become ordinary lowercase nouns.
An eponym is not the same as a homonym, which is a word that sounds or looks like another word but has a different meaning. A synonym shares meaning with another word, while an acronym is formed from initial letters or parts of a phrase.