But as everyone can agree, the word is everywhere and it's controversial.
"Vaccine" is Merriam-Webster's Word of the Year. The word was selected based on lookup data, notable spikes, and year-over-year increases in searches.
"This is a word that has kind of two parallel but intersecting stories: one is a medical story, and one is a political story or a cultural story," said Peter Sokolowski, Merriam-Webster's editor-at-large.
This selection comes after "pandemic" was chosen in 2020, which informed top searches on the site and reshaped daily language, according to the company. The Oxford English Dictionary selected "vax" as their word of the year.
"Vaccine" was selected, according to Merriam-Webster, because it is a promising medical solution which became a major source of political division. New research into vaccines led the company to revise and expand its entry for "vaccine" in May. An entry for "immune response," in which cells behave as though a disease is present to train the body to fight it, was added separate from "immunity."
"The 'messenger RNA vaccine' was new to me, I had never heard of it, and unless you were a research scientist, you probably haven't," Sokolowski told CNN. "Therefore, the dictionary didn't even cover a definition."
On the site, lookups for "vaccine" shot up 601% over 2020, especially toward the latter part of the year when the first US shot was administered in December.
There was a 1,048% increase in site lookups this year compared to 2019. This August, lookups of "vaccine" jumped 535% due to widespread distribution in parts of the world and major stories about policy, approval and vaccination rates. In August, the Pfizer vaccine received full FDA approval.
It was also the time when New York and California instituted vaccine mandates for healthcare workers, as well as national announcements about booster shots for the general public, which led to debates about inequities in vaccine distribution.
And searches have remained stable through late fall, especially with talk about the Omicron variant and the efficacy of vaccines in stopping it.
"Vaccine" also has a compelling etymology, according to Sokolowski. The word derives from the Latin word "vaccinus," meaning "of or from a cow." The Latin for cow is "vacca." The word later entered French as "vaccin," then into English with today's spelling.
Sokolowski believes people will continue to look up the word in high numbers for perhaps years to come, as the term "vaccine" becomes a more regular feature of daily life.
One notable runner-up word was "insurrection," searches for which increased by 61,000% on January 7, the day after the January 6 siege on the US Capitol. Searches continued throughout the year with more arrests and congressional hearings. Sokolowski noted the word "embodied the shock of that day" because of its derivation from Latin, which originally had strong legal meaning.
According to Sokolowski, people turn to the dictionary in times of uncertainty and urgency. The dictionary is a way to achieve a consensus, which "doesn't mean that we agree with each other on the policies, but that we agree with the words that we use as carrying meaning and having a specific meaning."
Another runner-up was "perseverance," the name of NASA's latest Mars rover, which landed February 18. The name was chosen by a seventh-grader in Virginia who participated in an essay contest organized by NASA.
The word "woke" also made the top 10, which fascinated Sokolowski because of how quickly the definition changed. Five years ago, "woke" referred to "a kind of enlightened awareness," but it now serves as an "epithet to argue against the acknowledgment of what some would call progressive ideas or some would call revisionist history."
The word "guardian" shot up 3,142% this year mainly because Cleveland's MLB team changed its name from the Indians to the Guardians to remove a term many called culturally insensitive or politically incorrect.
"We are in a period of time when terms of identity, whether it's transgender identity, racial identity, ethnic identity, the pronouns that we use... are the object of a huge amount of concentrated attention in our language," Sokolowski acknowledged.
Other top words include infrastructure, cicada, meta, nomad, cisgender, and murraya -- a tropical tree and the winning word for the 2021 Scripps National Spelling Bee.
"In controversial times or uncertain times, there is this neutral and objective arbiter of meaning and that is the dictionary," Sokolowski contended. "That's why we revise constantly to make sure our dictionary is accurate, but it also means that there is a sort of constant."