[vak-seen or, especially Brit., vak-seen, -sin] 
| 1. | any preparation used as a preventive inoculation to confer immunity against a specific disease, usually employing an innocuous form of the disease agent, as killed or weakened bacteria or viruses, to stimulate antibody production. |
| 2. | the virus of cowpox, used in vaccination, obtained from pox vesicles of a cow or person. |
| 3. | a software program that helps to protect against computer viruses, as by detecting them and warning the user. |
| 4. | of or pertaining to vaccination. |
| 5. | of or pertaining to vaccinia. |
| 6. | of, pertaining to, or derived from cows. |
| vac·cine (vāk-sēn', vāk'sēn') n.
[From Latin vaccīnus, of cows, from vacca, cow.] |
A substance prepared from dead or living microorganisms that is introduced into the body through inoculation. The vaccine causes the development of antibodies, which produce immunity to the disease caused by the microorganism.
vaccine vac·cine (vāk-sēn' vāk'sēn')
n.
A preparation of a weakened or killed pathogen, such as a bacterium or virus, or of a portion of the pathogen's structure that upon administration stimulates antibody production against the pathogen but is incapable of causing severe infection.
A vaccine prepared from the cowpox virus and inoculated against smallpox.