Unlike Oxford, Merriam-Webster named "science" its choice for this year's word with number two on the list being "cognitive".
Oxford's choice of "selfie" last month was a result of the word's growing usage and digital fame. But its US counterpart picked "science" primarily based on numbers on its website.
Selfie had beaten 'twerk' -- a raunchy dance move performed by Miley Cyrus -- to be named the word of the year by the Oxford Dictionaries.
However, Twerk did not figure on the list named by Merriam-Webster, CNN reported.
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The word with the largest spike was 'science'. A 176 per cent increase in look-ups, to be exact.
"A wide variety of discussions centred on science this year, from climate change to educational policy," the dictionary editors said in a statement.
"We saw heated debates about 'phony' science, or whether science held all the answers. It's a topic that has great significance for us," the editors said.
Merriam-Webster has a history of not getting too carried away by Internet memes.