Sheathbill \Sheath"bill`\, n. (Zool.)
Either one of two species of birds composing the genus
{Chionis}, and family {Chionidae}, native of the islands of
the Antarctic seas.
[1913 Webster]
Note: They are related to the gulls and the plovers, but more
nearly to the latter. The base of the bill is covered
with a saddle-shaped horny sheath, and the toes are
only slightly webbed. The plumage of both species is
white.
[1913 Webster]