walrus(n = noun.animal) sea horse, seahorse - either of two large northern marine mammals having ivory tusks and tough hide over thick blubber;
is a kind of pinnatiped, pinniped, pinniped mammal
is a member of genus odobenus, odobenus
has particulars: atlantic walrus, odobenus rosmarus, odobenus divergens, pacific walrus

   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]
" 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]

walrus, n. a large amphibious long-tusked arctic mammal, Odobenus rosmarus, related to the seal and sea lion.

Idiom:
walrus moustache a long thick drooping moustache.

Etymology:
prob. f. Du. walrus, -ros, perh. by metath. after walvisch 'whale-fish' f. word repr. by OE horschw{aelig}l 'horse-whale'

atlantic walrus, pacific walrus, walrus moustache, walrus mustache