The Collaborative International Dictionary of English v.0.48:

Immune \Im*mune"\, a. [L. immunis. See Immunity.]
   1. Exempt; protected. -- Im*mu"nize, v. t.
      [1913 Webster]

   2. (Med.) Protected from disease due to the action of the
      immune system, especially by having been inoculated
      against or previously exposed to a disease.
      [PJC]

   3. (Med.) Of or pertaining to the immune system or the
      components of the immune system.
      [PJC]

   4. Not responsive; as, immune to suggestion.
      [PJC]

WordNet (r) 3.0 (2006):

immunize
    v 1: law: grant immunity from prosecution [syn: immunize,
         immunise]
    2: perform vaccinations or produce immunity in by inoculation;
       "We vaccinate against scarlet fever"; "The nurse vaccinated
       the children in the school" [syn: immunize, immunise,
       inoculate, vaccinate]