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NEW Definition for the Vaccine

Prefatory note:  In this post, I take the noun “vaccine” as the basic word under discussion, but also consider other cognate terms (“vaccinate”, “vaccination”).

Here’s a standard dictionary entry for “vaccine”:

1. any preparation of weakened or killed bacteria or viruses introduced into the body to prevent disease by stimulating antibodies against it.
2. the virus of cowpox, used in vaccination, is obtained from the pox vesicles of a cow or person.
3. a software program that helps to protect against computer viruses.

[1800–05; < New Latin (variolae)vaccīnae cowpox = vacc(a) cow + -īnae, feminine pl. of -īnus -ine]

Random House Kernerman Webster’s College Dictionary


Let us compare that with the new M-W entry for “vaccine”:a preparation that is administered (as by injection) to stimulate the body’s immune response against a specific infectious disease:

a: an antigenic preparation of a typically inactivated or attenuated (see attenuated sense 2) pathogenic agent (such as a bacterium or virus) or one of its components or products (such as a protein or toxin)
ba preparation of genetic material (such as a strand of synthesized messenger RNA) that is used by the cells of the body to produce an antigenic substance (such as a fragment of virus spike protein)

Examples of the vaccine in a SentenceRecent Examples on the Web
//At the time, J&J had been committed to delivering 24 million doses of its vaccine to the U.S. by the end of April.

— Melissa Holzberg, Forbes, “FDA Issues Scathing Report Of Baltimore Warehouse Where Johnson & Johnson Vaccines Were Ruined,” 21 Apr. 2021

//Pfizer has asked the Food and Drug Administration for emergency use authorization of its vaccine in children ages 12 to 15.

— NBC News, “With vaccines open to 16- to 17-year-olds, high schools set up shop to give the shots,” 21 Apr. 2021First Known Use of the vaccine

1882, in the meaning defined above history and Etymology for vaccine

earlier,* “fluid from cowpox pustules used in inoculation,” noun use of vaccine “of cowpox” (in the phrases vaccine disease, vaccine matter), borrowed from New Latin vaccina (in variolae vaccinae “cowpox”), going back to Latin, feminine of vaccīnus “of or from a cow,” from vacca “cow” (perhaps akin to Sanskrit vaśā “cow”) + -īnus -ine entry 1; in extended sense, “preparation of organisms administered to produce immunity,” in part borrowed from French vaccin, masculine derivative of vaccine “cowpox, matter from cowpox pustules,” borrowed from New Latin or English

*VHM:  emphasis added

From the current M-W entry on “vaccination”:

Examples of vaccination in a Sentence
Recent Examples on the Web
//But if the operator demands proof of vaccination or a negative test, the venue can more than double capacity to 35%.
— oregonlive, “California’s reopening rules encourage venues to require proof of COVID-19 vaccination,” 20 Apr. 2021

//Two of them were within three weeks of full vaccination.
— Kristen Jordan Shamus, Detroit Free Press, “Sterling Heights couple among 334 statewide who got COVID-19 after being fully vaccinated,” 20 Apr. 2021 (source) Here are some additional etymologies for “vaccine” and “vaccination”: 

1800, used by British physician Edward Jenner (1749-1823) for the technique he publicized of preventing smallpox by injecting people with the similar but much milder cowpox virus (variolae vaccinae), from the vaccine (adj.) “pertaining to cows, from cows” (1798), from Latin vaccinus “from cows,” from vacca “cow,” a word of uncertain origin. A mild case of cowpox rendered one immune thereafter to smallpox. “The use of the term for diseases other than smallpox is due to Pasteur” [OED].

The earlier 18c. method of smallpox protection in England was by a kind of inoculation called  variolation (from variola, the medical Latin word for “smallpox”). There are two forms of smallpox: a minor one that killed 2% or less of the people who got it, and a virulent form that had about a 30% mortality rate and typically left survivors with severe scarring and often blinded them. Those who got the minor form were noted to be immune thereafter to the worse. Doctors would deliberately infect healthy young patients with a local dose of the minor smallpox, usually resulting in a mild case of it at worst, to render them immune to the more deadly form. Jenner’s method was safer, as it involved no smallpox exposure.

(Online Etymology Dictionary)

The terms vaccine and vaccination are derived from Variolae vaccine (smallpox of the cow), the term devised by Edward Jenner (who both developed the concept of vaccines and created the first vaccine) to denote cowpox. He used the phrase in 1798 for the long title of his Inquiry into the Variolae vaccine Known as the Cow Pox, in which he described the protective effect of cowpox against smallpox.[12] In 1881, to honor Jenner, Louis Pasteur proposed that the terms should be extended to cover the new protective inoculations then being developed. The science of vaccine development and production is termed vaccinology.


According to Wiktionary, Latin Vacca (“cow”) — also in Corsican, Dalmatian, Interlingua, Italian (descendant in Alemannic German [Wagge]), Romansch, Sardinian, and Sicilian — is from the Proto-Indo-European *woḱéh₂.  Wiktionary lists dozens of descendants in Romance languages.  (source)

A longer account of the derivation and nature of “vaccine” is given in the American Heritage Student Science Dictionary, 2nd ed.:

A substance that stimulates cells in the immune system to recognize and attack disease-causing agents, especially through the production of antibodies. Most vaccines are given by injection or are swallowed as liquids. Vaccines may contain a weaker form of the disease-causing virus or bacterium or even a DNA fragment or some other component of the agent. See Note at Jenner.

Did You Know? In the 1950s, polio epidemics left thousands of children with permanent physical disabilities. Today, kids are given a polio vaccine to keep them from catching the virus. That vaccine, like most others, works by stimulating the body’s immune system to produce antibodies—substances that defend the body against infection by recognizing and destroying disease-causing agents like viruses and bacteria. Scientists usually prepare vaccines by taking a sample of the disease-causing agent and weakening it with heat or chemicals. That way, the agent loses its ability to cause serious illness but is still able to stimulate the body to produce antibodies and provide immunity. But finding safe vaccines that are also effective is a challenge. Today, scientists are able to change the structure of viruses and bacteria at the level of their DNA. They remove the most harmful fragments of DNA and then use what is left in vaccines. New vaccines containing harmless bits of DNA from disease-causing germs have also been developed—all to make diseases like polio a thing of the past.


To refresh our memory, here’s the new M-W “b” definition for “vaccine”: a preparation of genetic material (such as a strand of synthesized messenger RNA) that is used by the cells of the body to produce an antigenic substance (such as a fragment of virus spike protein) Compare the new M-W “b” definition of “vaccine” with this statement from the CDC:

COVID-19 mRNA vaccines give instructions for our cells to make a harmless piece of what is called the “spike protein.” The spike protein is found on the surface of the virus that causes COVID-19.

To determine when the new “b” definition was added to the entry for “vaccine” by M-W, I read through all the screenshots for that entry on Wayback Machine of the Internet Archive beginning from January, 2019.  The first time the new definition (“b”) occurs is on January 26, 2021 at 06:51:43.

I wonder if and when other dictionaries will follow suit. 

April 30, 2021 @ 9:10 am · Filed by Victor Mair under EtymologyLanguage and medicineLexicon and lexicography


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3 thoughts on “The “vaccine” Has a NEW Definition”
  1. it is not uncommon for definitions to evolve as scientific research advances. There are many common everyday words whose definitions had to be updated to meet current meaning and usage; mouse, tablet, calculator, spam, drone, and hundreds of others.

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