: a preparation containing usually killed or weakened microorganisms (as bacteria or viruses) that is given usually by injection to increase protection against a particular disease
Word History of VACCINE
In the late 1700s the English doctor Edward Jenner investigated the old belief that people who contracted a mild disease called cowpox from cows thereby became immune to smallpox, a much more dangerous disease. Jenner documented 23 such cases, where people inoculated with matter from cowpox sores came down with cowpox but then did not contract smallpox. Because variolae vaccinae, literally, “cow pustules,” was the medical Latin name for cowpox, the virus-containing material used for inoculations eventually came to be called vaccine.
nounvac·cine \vak-ˈsēn, ˈvak-ˌ\
Medical Definition of VACCINE
: matter or a preparation containing the virus of cowpox used to vaccinate a person against smallpox
: a preparation of killed microorganisms, living attenuated organisms, or living fully virulent organisms that is administered to produce or artificially increase immunity to a particular disease <chicken pox vaccine>; also: a mixture of several such vaccines <measles-mumps-rubella vaccine>