Wiktionary:Word of the day/2023/January 26

1. (historical)
   1. (medicine) Of, pertaining to, caused by, or characteristic of cowpox.
   2. (by extension, immunology) Of or pertaining to cowpox as a source of material for vaccination against smallpox; also, of or pertaining to such material used for vaccination.
2. (archaic) Of, pertaining to, or derived from cattle or cows.

vaccine n

1. (immunology)
   1. A substance given to stimulate a body's production of antibodies and provide immunity against a disease without causing the disease itself in the treatment, prepared from the agent that causes the disease (or a derivative of it; or a related, also effective, but safer disease), or a synthetic substitute; also, a dose of such a substance.
   2. The process of vaccination; immunization, inoculation.
   3. (historical) Material taken from cowpox pustules used for vaccination against smallpox.
   4. (also medicine, obsolete) The disease cowpox, especially as a source of material for vaccination against smallpox.
2. (figuratively)
   1. Something defensive or protective in nature, like a vaccine (sense 1.1).
   2. (computing) A software program which protects computers against, or detects and neutralizes, computer viruses and other types of malware; an antivirus.

vaccine v

1. (transitive, archaic) Synonym of vaccinate (“to treat (a person or an animal) with a vaccine to produce immunity against a disease”)

The British physician and scientist Edward Jenner, who pioneered the concept of vaccines and created the world’s first vaccine—the smallpox vaccine, died on this day 200 years ago in 1823.