The Collaborative International Dictionary of English v.0.48:

Rabid \Rab"id\ (r[a^]b"[i^]d), a. [L. rabidus, from rabere to
   rave. See Rage, n.]
   1. Furious; raging; extremely violent.
      [1913 Webster]

            The rabid flight
            Of winds that ruin ships.             --Chapman.
      [1913 Webster]

   2. Extreme, unreasonable, or fanatical in opinion;
      excessively zealous; as, a rabid socialist.
      [1913 Webster]

   3. Affected with the distemper called rabies; mad; as, a
      rabid dog or fox.
      [1913 Webster]

   4. (Med.) Of or pertaining to rabies, or hydrophobia; as,
      rabid virus.
      [1913 Webster]

WordNet (r) 3.0 (2006):

rabid
    adj 1: of or infected by rabies
    2: marked by excessive enthusiasm for and intense devotion to a
       cause or idea; "rabid isolationist" [syn: fanatic,
       fanatical, overzealous, rabid]