Word Study
Narwhal
CIDE DICTIONARY
Narwhal, n. [Sw. or Dan. narvhal; akin to Icel. nāhvalr, and E. whale. the first syllable is perh. from Icel. nār corpse, dead body, in allusion to the whitish color its skin. See Whale.].
An arctic cetacean (Monodon monocerous ), about twenty feet long. The male usually has one long, twisted, pointed canine tooth, or tusk, projecting forward from the upper jaw like a horn, whence it is called also sea unicorn , unicorn fish , and unicorn whale . Sometimes two horns are developed, side by side. [1913 Webster]
OXFORD DICTIONARY
Narwhal, n. an Arctic white whale, Monodon monoceros, the male of which has a long straight spirally fluted tusk developed from one of its teeth. Also called BELUGA.
Etymology
Du. narwal f. Da. narhval f. hval whale: cf. ON n{aacute}hvalr (perh. f. n{aacute}r corpse, with ref. to its skin-colour)
For further exploring for "Narwhal" in Webster Dictionary Online