The Collaborative International Dictionary of English v.0.48:

Hydrophobia \Hy`dro*pho"bi*a\, n. [L., fr. Gr. ?; "y`dwr water +
   ? fear: cf. F. hydrophobie.] (Med.)
   (a) An abnormal dread of water, said to be a symptom of
       canine madness; hence:
   (b) A viral disease trransmitted by a bite from, or
       inoculation with the saliva of, a rabid creature, of
       which the chief symptoms are, a sense of dryness and
       constriction in the throat, causing difficulty in
       deglutition, and a marked heightening of reflex
       excitability, producing convulsions whenever the patient
       attempts to swallow, or is disturbed in any way, as by
       the sight or sound of water; rabies; canine madness.
       [Written also hydrophoby.]
       [1913 Webster]

WordNet (r) 3.0 (2006):

hydrophobia
    n 1: a symptom of rabies in humans consisting of an aversion to
         swallowing liquids
    2: a morbid fear of water
    3: an acute viral disease of the nervous system of warm-blooded
       animals (usually transmitted by the bite of a rabid animal);
       rabies is fatal if the virus reaches the brain [syn:
       rabies, hydrophobia, lyssa, madness]