The New York Times recently added an entry to its eponymous stylebook, available only online:

“In precise, traditional usage, an eponym is someone who gives a name to something else, and eponymous describes the giver of the name, not the receiver. A restaurateur named Terry Lamb could be described as the eponymous owner of Terry Lamb’s Restaurant, but the establishment is not Mr. Lamb’s eponymous restaurant.”

The receiver of the “eponym’s” name is its “namesake,” and the Times added an entry for that as well.

That means the Times is the “eponym” and is the “eponymous” creator of its Manual of Style and Usage; the stylebook itself is the Times’ “namesake,” and describing the stylebook as “eponymous” is against Times style.

But while dictionaries agree that “eponym,” the noun, always refers to the person bestowing the name, of the major dictionaries, only Webster’s New World (the dictionary used by the Times and The Associated Press, among other media), retains the insistence that “eponymous” the adjective refers only to the person who is lending the name. The American Heritage Dictionary of the English Language (Fifth Edition), for example, defines “eponymous” as “Named after something else or deriving from an existing name or word: ‘Programs such as He-Man and Masters of the Universe . . . were all created with the explicit purpose of selling the eponymous toys to children.’ “

Common usage seems to employ both “eponym” and “eponymous” as much to refer to the named thing as to the name giver. There’s even an Eponyms app, for medical students, that lists diseases and conditions named after people, like Hashimoto’s thyroiditis. It describes only the namesake condition, not the person for whom it’s named.

Garner’s Modern American Usage says that “today, eponymous is commonly (and sloppily) used with the derived name rather than the eponym itself.” Using “eponym” instead of “namesake” remains, in the view of the book’s eponym, as well as that of the Times, unacceptable name-calling.

Staying out of this trap is easy: Use 10-cent words like “named for” or “namesake” instead of the $50 word “eponym.”

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Merrill Perlman managed copy desks across the newsroom at The New York Times, where she worked for 25 years. Follow her on Twitter at @meperl.