Narwhal
Narwhal (nar"hwȧl) , noun
[Swedish or Danish narvhal; akin to Icelandic nāhvalr, and English whale. the first syllable is perh. from Icelandic nār corpse, dead body, in allusion to the whitish color its skin. See Whale.]
(Zoology) 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.