English▸ noun a substance used to stimulate the production of antibodies and provide immunity against one or several diseases, prepared from the causative agent of a disease, its products, or a synthetic substitute, treated to act as an antigen without inducing the disease:
there is no vaccine against the virus.
▪ Computing a program designed to detect computer viruses and inactivate them.
– ORIGIN late 18th century : from Latin vaccinus, from vacca ‘cow’ (because of the early use of the cowpox virus against smallpox).