The United States dictionary said there has been a substantial increase in searches for "authentic" during 2023 - which it defined in part as "not false or imitation".
"The rise of AI helped drive interest in the word," said Merriam-Webster editor at large Peter Sokolowski.
"The line between 'real' and 'fake' has become increasingly blurred."
While Merriam-Webster's word of 2023 was "authentic" the Cambridge dictionary chose "hallucinate" - in reference to an AI hallucinating and producing false information.
Irnically the Collins dictionary chose "AI" - the abbreviation for artificial intelligence - as its word of the year.
Merriam-Webster said other words stood out in searches this year, including "rizz" - which is internet slang for "romantic appeal or charm" as a noun and "to charm or seduce" as a verb; "deepfake" meaning an image or recording altered to misrepresent what someone has said or done; and "coronation" during the crowning of King Charles III in May.
