n 1  :  matter or a preparation containing the virus of cowpox in a form used for vaccination  2  :  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 <polio >  : also  :  a mixture of several such vaccines <measles-mumps-rubella >  .
 
   
 
Similar sounding terms:  fu·co·san  vac·ci·nee  vac·cin·ia 
 
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