The most looked-up word in 2015? Socialism.

Politics, current events, and crises drove the most looked-up words of the year on Merriam-Webster, which chose "ism" as its "word of the year."

The most looked-up word? Socialism, which saw a 169 percent increase in lookups since 2014. The dictionary publisher attributes it to US presidential candidate Bernie Sanders, a self-described democratic socialist.

“Socialism has been near the top of our online dictionary look-up list for several years,” said M-W editor-at-large Peter Sokolowski. “However, this year look-ups for socialism moved up even further, beginning with the July campaign events for Bernie Sanders, remaining high throughout the following months and spiking again after the first Democratic debate in October.”

The second most lookup-up word was fascism, which saw a spike in lookups following Donald Trump's remarks about banning Muslims from entering the US.

Other "isms" M-W cited include terrorism, looked up following the Paris, Colorado Springs and San Bernardino attacks; racism, prompted by the South Carolina church shooting, the University of Missouri protests and incidents of police violence; and feminism, thanks to Amy Schumer’s success, Hillary Clinton’s candidacy and coverage of Caitlyn Jenner’s story.

“We had a lot on our minds this year,” Mr. Sokolowski told the Associated Press. “It’s a serious year. These are words of ideas and practices. We’re educating ourselves.”

Of course, the foremost topic on which Americans were educating themselves, according to the most lookups, was socialism.

In its post announcing its words of the year, M-W said that Sanders' embrace of socialism "shows that the term has moved beyond its Cold War associations."

In fact, it even prompted the dictionary publisher to update its dictionary entry on the word.

Pure socialism has been seen only rarely and generally briefly in some Communist regimes, according to M-W.

“Far more common are systems of social democracy, now often referred to as ‘democratic socialism,’ in which extensive state regulation, with limited state ownership, has been employed by democratically elected governments (as in Sweden and Denmark) in the belief that it produces a fair distribution of income without impairing economic growth,” it wrote in explaining its definition.

Two more "isms," communism and capitalism, round out the list of seven words that represent “millions of individual look-ups” over the last year, according to M-W.

M-W isn't the only dictionary publisher to choose an unconventional word of the year. Last month, Oxford Dictionaries  chose an emoji, the one whose verbal description is “face with tears of joy," as its word of the year.