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]

The Collaborative International Dictionary of English v.0.48:

Immune \Im*mune"\, n.
   One who is immune; esp., a person who is immune from a
   disease by reason of previous affection with the disease or
   inoculation.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

immune
    adj 1: relating to the condition of immunity; "the immune
           system"
    2: secure against; "immune from taxation as long as he resided
       in Bermuda"; "immune from criminal prosecution"
    3: relating to or conferring immunity (to disease or infection)
       [syn: immune, resistant]
    4: (usually followed by `to') not affected by a given influence;
       "immune to persuasion"
    n 1: a person who is immune to a particular infection

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "immune":
   chartered, excepted, excused, exempt, exempted, favored, immunized,
   inoculated, insured, insusceptible, intact, invulnerable,
   irresponsible, let off, licensed, nonsusceptible to disease,
   permitted, privileged, protected, released, resistant, safe,
   safe and sound, secure, spared, unaccountable, unaffected,
   unanswerable, undamaged, unharmed, unhurt, unliable, unscathed,
   unsubject, unsusceptible, unthreatened, untouched, vaccinated