The Collaborative International Dictionary of English v.0.48:

Gray \Gray\ (gr[=a]), a. [Compar. Grayer; superl. Grayest.]
   [OE. gray, grey, AS. gr[=ae]g, gr[=e]g; akin to D. graauw,
   OHG. gr[=a]o, G. grau, Dan. graa, Sw. gr[*a], Icel. gr[=a]r.]
   [Written also grey.]
   1. any color of neutral hue between white and black; white
      mixed with black, as the color of pepper and salt, or of
      ashes, or of hair whitened by age; sometimes, a dark mixed
      color; as, the soft gray eye of a dove.
      [1913 Webster]

            These gray and dun colors may be also produced by
            mixing whites and blacks.             --Sir I.
                                                  Newton.
      [1913 Webster]

   2. Gray-haired; gray-headed; of a gray color; hoary.
      [1913 Webster]

   3. Old; mature; as, gray experience. -- Ames.
      [1913 Webster]

   4. gloomy; dismal.
      [PJC]

   Gray antimony (Min.), stibnite.

   Gray buck (Zool.), the chickara.

   Gray cobalt (Min.), smaltite.

   Gray copper (Min.), tetrahedrite.

   Gray duck (Zool.), the gadwall; also applied to the female
      mallard.

   Gray falcon (Zool.) the peregrine falcon.

   Gray Friar. See Franciscan, and Friar.

   Gray hen (Zool.), the female of the blackcock or black
      grouse. See Heath grouse.

   Gray mill or Gray millet (Bot.), a name of several plants
      of the genus Lithospermum; gromwell.

   Gray mullet (Zool.) any one of the numerous species of the
      genus Mugil, or family Mugilid[ae], found both in the
      Old World and America; as the European species
      (Mugilid[ae] capito, and Mugilid[ae] auratus), the
      American striped mullet (Mugilid[ae] albula), and the
      white or silver mullet (Mugilid[ae] Braziliensis). See
      Mullet.

   Gray owl (Zool.), the European tawny or brown owl (Syrnium
      aluco). The great gray owl (Ulula cinerea) inhabits
      arctic America.

   Gray parrot (Zool.), an African parrot (Psittacus
      erithacus), very commonly domesticated, and noted for its
      aptness in learning to talk. Also called jako.

   Gray pike. (Zool.) See Sauger.

   Gray snapper (Zool.), a Florida fish; the sea lawyer. See
      Snapper.

   Gray snipe (Zool.), the dowitcher in winter plumage.

   Gray whale (Zool.), a rather large and swift whale of the
      northern Pacific (Eschrichtius robustus, formerly
      Rhachianectes glaucus), having short jaws and no dorsal
      fin. It grows to a length of 50 feet (someimes 60 feet).
      It was formerly taken in large numbers in the bays of
      California, and is now rare; -- called also grayback,
      devilfish, and hardhead. It lives up to 50 or 60 years
      and adults weigh from 20 to 40 tons.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Grayback \Gray"back`\, n. (Zool.)
   (a) The California gray whale.
   (b) The redbreasted sandpiper or knot.
   (c) The dowitcher.
   (d) The body louse.
       [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Gray whale \Gray whale\ (Zool.),
   a rather large and swift baleen whale of the northern Pacific
   (Eschrichtius robustus, formerly Rhachianectes glaucus),
   having short jaws and no dorsal fin; -- called also
   grayback, devilfish, and hardhead. It grows to a length
   of 50 feet (sometimes 60 feet). It was formerly taken in
   large numbers in the bays of California, and is now rare. It
   lives up to 50 or 60 years and adults weigh from 20 to 40
   tons.
   [1913 Webster + PJC]

The Collaborative International Dictionary of English v.0.48:

Redhead \Red"head`\ (-h?d`), n.
   1. A person having red hair.
      [1913 Webster]

   2. (Zool.)
      (a) An American duck (Aythya Americana) highly esteemed
          as a game bird. It is closely allied to the
          canvasback, but is smaller and its head brighter red.
          Called also red-headed duck. American poachard,
          grayback, and fall duck. See Illust. under
          Poachard.
      (b) The red-headed woodpecker. See Woodpecker.
          [1913 Webster]

   3. (Bot.) A kind of milkweed (Asclepias Curassavica) with
      red flowers. It is used in medicine.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dowitcher \Dow"itch*er\, n. (Zool.)
   The red-breasted or gray snipe (Macrorhamphus griseus); --
   called also brownback, and grayback.
   [1913 Webster]

WordNet (r) 3.0 (2006):

grayback
    n 1: a dowitcher with a grey back [syn: greyback, grayback,
         Limnodromus griseus]
    2: a sandpiper that breeds in the Arctic and winters in the
       southern hemisphere [syn: knot, greyback, grayback,
       Calidris canutus]