Source : Webster's Revised Unabridged Dictionary (1913)

Water deer \Wa"ter deer`\ (Zo["o]l.)
   (a) A small Chinese deer ({Hydropotes inermis}). Both sexes
       are destitute of antlers, but the male has large,
       descending canine tusks.
   (b) The water chevrotain.

Source : WordNet®

water deer
     n : largest chevrotain; of marshy areas of west Africa [syn: {water
         chevrotain}, {Hyemoschus aquaticus}]