The good folks and lexicographers at Merriam-Webster calculate interest in and impact of a given word by how often people look it up online. It’s an interesting snapshot of the decade to look back at the last ten Words of the Year, along with new terms added to the dictionary.
2012: Socialism and capitalism
2015: -ism (Socialism, Fascism, Racism, Feminism, Communism)
New words from the first half of the decade: fist bump, tweet, bromance, parkour, man cave, underwater, earworm, bucket list, gastropub, twerking, hashtag, selfie, catfish, unfriend, crowdfunding, big data, emoji, net neutrality, meme, clickbait, jegging, NSFW
2019: They—gender neutral pronoun to be used in place of "he" or "she"
New words: gig economy, swole, stan, deep state, dad joke, FOMO, revenge porn, froyo, weak sauce, photobomb, listicle, facepalm, bougie, TL;DR, bingeable, airplane mode, fintech, zoodle, Latinx
Go forth into 2020 with a refreshed vocabulary, friends. And Happy New Year!