walrus \wal"rus\, n. d. walrus; of scand. origin; cf. dan
   valros, sw. vallross, norw. hvalros; literally, whale horse;
   akin to icel. hrosshvalr, as. horshwael. see whale, and
   horse. zool.
   a very large marine mammal trichecus rosmarus of the seal
   family, native of the arctic ocean. the male has long and
   powerful tusks descending from the upper jaw. it uses these
   in procuring food and in fighting. it is hunted for its oil,
   ivory, and skin. it feeds largely on mollusks. called also
   morse.
   1913 webster

   note: the walrus of the north pacific and behring strait
         trichecus obesus is regarded by some as a distinct
         species, by others as a variety of the common walrus.
         1913 webster
see also:
whale horse trichecus rosmarus morse trichecus obesus