\Nar"whal\, n. [Sw. or Dan. narvhal; akin to Icel.
n[=a]hvalr, and E. whale. the first syllable is perh. from
Icel. n[=a]r corpse, dead body, in allusion to the whitish
color its skin. See {Whale}.] [Written also {narwhale}.]
(Zo["o]l.)
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.