an arctic toothed whale (Monodon monoceros) of the same family (Monodontidae) as the beluga, valued for its oil and ivory: the male has a long, spiral tusk extending from the upper jaw
Origin:
< Scand, as in Norw & Dan narhval < ON nahvalr, lit., corpse (< IE base *nāu-, death, corpse) + hvalr, whale (with reference to the whitish underside)