vaccinia

from WordNet (r) 3.0 (2006)

vaccinia
    n 1: a local infection induced in humans by inoculation with the
         virus causing cowpox in order to confer resistance to
         smallpox; normally lasts three weeks and leaves a pitted
         scar [syn: {vaccinia}, {vaccina}, {variola vaccine},
         {variola vaccinia}, {variola vaccina}]
    2: a viral disease of cattle causing a mild skin disease
       affecting the udder; formerly used to inoculate humans
       against smallpox [syn: {cowpox}, {vaccinia}]

from The Collaborative International Dictionary of English v.0.48

Vaccinia \Vac*cin"i*a\, n. [NL. See {Vaccine}.] (Med.)
   Cowpox; vaccina. See {Cowpox}.
   [1913 Webster]