But not just any ism. The top isms to earn high traffic spikes and big bumps in lookups on the dictionary company's website in 2015 over the year before are socialism, fascism, racism, feminism, communism, capitalism and terrorism.
"We had a lot on our minds this year," mused Peter Sokolowski, the Springfield, Massachusetts-based company's editor at large, in a recent interview. "It's a serious year. These are words of ideas and practices. We're educating ourselves."
Pinpointing reasons why words go on the run at Merriam-Webster is an educated guess. The dictionary company tracks corresponding news events to link lookups to real life.
Lookups for fascism corresponded to release of video in November showing a white police officer shooting a black teenager in Chicago, and the criminal charges that followed.
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Merriam-Webster also saw a stronger correlation in heavy traffic on its site for that word and "fascist" and flash points in Republican Donald Trump's presidential campaign, including reports on his anti-Islam rhetoric.
The isms often collide, driving each other in popularity, Sokolowski said.
"Fascism we more closely associate as the response to various acts of terrorism. After the attacks in Paris and the attacks in Colorado Springs and in San Bernardino, and because of Donald Trump's proposal to ban Muslims, we then see the word fascism spike," he said.
Sokolowski, a lexicographer by training, said one spike in lookups for feminism came in April and corresponded with reports on an Ohio middle school student who wore a T-shirt with the word printed on it in a school photo, only to have it digitally blacked out by school administrators. The school later apologised.
Reports on Caitlyn Jenner, Amy Schumer and Hillary Clinton all included discussion of feminism, as did reviews of the film "Mad Max: Fury Road" and chatter about previews of "Star Wars: The Force Awakens."