The Collaborative International Dictionary of English v.0.48:

Vaccine \Vac"cine\ (v[a^]k"s[imac]n or v[a^]k"s[i^]n; 277), a.
   [L. vaccinus, fr. vacca a cow; cf. Skr. v[=a][,c] to bellow,
   to groan.]
   1. Of or pertaining to cows; pertaining to, derived from, or
      caused by, vaccinia; as, vaccine virus; the vaccine
      disease.
      [1913 Webster]

   2. Of or pertaining to a vaccine or vaccination.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Vaccine \Vac"cine\ (v[a^]k*s[=e]n" or v[a^]k"s[=e]n), n.
   1. The virus of vaccinia used in vaccination.
      [1913 Webster]

   2. any preparation used to render an organism immune to some
      disease, by inducing or increasing the natural immunity
      mechanisms. Prior to 1995, such preparations usually
      contained killed organisms of the type for which immunity
      was desired, and sometimes used live organisms having
      attenuated virulence. Since that date, preparations
      containing only specific antigenic portions of the
      pathogenic organism have also been used. Some of these are
      prepared by genetic engineering techniques.
      [PJC]

   3. (Computers) A program designed to protect a computer from
      software viruses, by detecting and or eliminating them.
      [PJC]

WordNet (r) 3.0 (2006):

vaccine
    n 1: immunogen consisting of a suspension of weakened or dead
         pathogenic cells injected in order to stimulate the
         production of antibodies [syn: vaccine, vaccinum]

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "vaccine":
   A, B, T, antitoxin, autogenous vaccine, bang, booster,
   booster shot, bovine vaccine, fix, hit, humanized vaccine,
   hypodermic, hypodermic injection, injection, inoculation,
   jet injection, mainlining, narcotic injection, shooting up, shot,
   skin-popping, stock vaccine, toxoid, univalent vaccine,
   vaccination