The Collaborative International Dictionary of English v.0.48:

Fox \Fox\ (f[o^]ks), n.; pl. Foxes. [AS. fox; akin to D. vos,
   G. fuchs, OHG. fuhs, foha, Goth. fa['u]h[=o], Icel. f[=o]a
   fox, fox fraud; of unknown origin, cf. Skr. puccha tail. Cf.
   Vixen.]
   1. (Zool.) A carnivorous animal of the genus Vulpes, family
      Canid[ae], of many species. The European fox (V.
      vulgaris or V. vulpes), the American red fox (V.
      fulvus), the American gray fox (V. Virginianus), and
      the arctic, white, or blue, fox (V. lagopus) are
      well-known species.
      [1913 Webster]

   Note: The black or silver-gray fox is a variety of the
         American red fox, producing a fur of great value; the
         cross-gray and woods-gray foxes are other varieties of
         the same species, of less value. The common foxes of
         Europe and America are very similar; both are
         celebrated for their craftiness. They feed on wild
         birds, poultry, and various small animals.
         [1913 Webster]

               Subtle as the fox for prey.        --Shak.
         [1913 Webster]

   2. (Zool.) The European dragonet.
      [1913 Webster]

   3. (Zool.) The fox shark or thrasher shark; -- called also
      sea fox. See Thrasher shark, under Shark.
      [1913 Webster]

   4. A sly, cunning fellow. [Colloq.]
      [1913 Webster]

            We call a crafty and cruel man a fox. --Beattie.
      [1913 Webster]

   5. (Naut.) Rope yarn twisted together, and rubbed with tar;
      -- used for seizings or mats.
      [1913 Webster]

   6. A sword; -- so called from the stamp of a fox on the
      blade, or perhaps of a wolf taken for a fox. [Obs.]
      [1913 Webster]

            Thou diest on point of fox.           --Shak.
      [1913 Webster]

   7. pl. (Ethnol.) A tribe of Indians which, with the Sacs,
      formerly occupied the region about Green Bay, Wisconsin;
      -- called also Outagamies.
      [1913 Webster]

   Fox and geese.
      (a) A boy's game, in which one boy tries to catch others
          as they run one goal to another.
      (b) A game with sixteen checkers, or some substitute for
          them, one of which is called the fox, and the rest the
          geese; the fox, whose first position is in the middle
          of the board, endeavors to break through the line of
          the geese, and the geese to pen up the fox.

   Fox bat (Zool.), a large fruit bat of the genus Pteropus,
      of many species, inhabiting Asia, Africa, and the East
      Indies, esp. P. medius of India. Some of the species are
      more than four feet across the outspread wings. See Fruit
      bat.

   Fox bolt, a bolt having a split end to receive a fox wedge.


   Fox brush (Zool.), the tail of a fox.

   Fox evil, a disease in which the hair falls off; alopecy.


   Fox grape (Bot.), the name of two species of American
      grapes. The northern fox grape (Vitis Labrusca) is the
      origin of the varieties called Isabella, Concord,
      Hartford, etc., and the southern fox grape (Vitis
      vulpina) has produced the Scuppernong, and probably the
      Catawba.

   Fox hunter.
      (a) One who pursues foxes with hounds.
      (b) A horse ridden in a fox chase.

   Fox shark (Zool.), the thrasher shark. See Thrasher
      shark, under Thrasher.

   Fox sleep, pretended sleep.

   Fox sparrow (Zool.), a large American sparrow (Passerella
      iliaca); -- so called on account of its reddish color.

   Fox squirrel (Zool.), a large North American squirrel
      (Sciurus niger, or S. cinereus). In the Southern
      States the black variety prevails; farther north the
      fulvous and gray variety, called the cat squirrel, is
      more common.

   Fox terrier (Zool.), one of a peculiar breed of terriers,
      used in hunting to drive foxes from their holes, and for
      other purposes. There are rough- and smooth-haired
      varieties.

   Fox trot, a pace like that which is adopted for a few
      steps, by a horse, when passing from a walk into a trot,
      or a trot into a walk.

   Fox wedge (Mach. & Carpentry), a wedge for expanding the
      split end of a bolt, cotter, dowel, tenon, or other piece,
      to fasten the end in a hole or mortise and prevent
      withdrawal. The wedge abuts on the bottom of the hole and
      the piece is driven down upon it. Fastening by fox wedges
      is called foxtail wedging.

   Fox wolf (Zool.), one of several South American wild dogs,
      belonging to the genus Canis. They have long, bushy
      tails like a fox.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Squirrel \Squir"rel\ (skw[~e]r"r[e^]l or skw[i^]r"-; 277), n.
   [OE. squirel, OF. esquirel, escurel, F. ['e]cureuil, LL.
   squirelus, squirolus, scuriolus, dim. of L. sciurus, Gr.
   si`oyros; skia` shade + o'yra` tail. Cf. Shine, v. i.]
   1. (Zool.) Any one of numerous species of small rodents
      belonging to the genus Sciurus and several allied genera
      of the family Sciuridae. Squirrels generally have a
      bushy tail, large erect ears, and strong hind legs. They
      are commonly arboreal in their habits, but many species
      live in burrows.
      [1913 Webster]

   Note: Among the common North American squirrels are the gray
         squirrel (Sciurus Carolinensis) and its black
         variety; the fox, or cat, squirrel (Sciurus cinereus,
         or Sciurus niger) which is a large species, and
         variable in color, the southern variety being
         frequently black, while the northern and western
         varieties are usually gray or rusty brown; the red
         squirrel (see Chickaree); the striped, or chipping,
         squirrel (see Chipmunk); and the California gray
         squirrel (Sciurus fossor). Several other species
         inhabit Mexico and Central America. The common European
         species (Sciurus vulgaris) has a long tuft of hair on
         each ear. The so-called Australian squirrels are
         marsupials. See Petaurist, and Phalanger.
         [1913 Webster]

   2. One of the small rollers of a carding machine which work
      with the large cylinder.
      [1913 Webster]

   Barking squirrel (Zool.), the prairie dog.

   Federation squirrel (Zool.), the striped gopher. See
      Gopher, 2.

   Flying squirrel (Zool.). See Flying squirrel, in the
      Vocabulary.

   Java squirrel. (Zool.). See Jelerang.

   Squirrel corn (Bot.), a North American herb (Dicentra
      Canadensis) bearing little yellow tubers.

   Squirrel cup (Bot.), the blossom of the Hepatica triloba,
      a low perennial herb with cup-shaped flowers varying from
      purplish blue to pink or even white. It is one of the
      earliest flowers of spring.

   Squirrel fish. (Zool.)
      (a) A sea bass (Serranus fascicularis) of the Southern
          United States.
      (b) The sailor's choice (Diplodus rhomboides).
      (c) The redmouth, or grunt.
      (d) A market fish of Bermuda (Holocentrum Ascensione).


   Squirrel grass (Bot.), a pestiferous grass (Hordeum
      murinum) related to barley. In California the stiffly
      awned spikelets work into the wool of sheep, and into the
      throat, flesh, and eyes of animals, sometimes even
      producing death.

   Squirrel hake (Zool.), a common American hake (Phycis
      tenuis); -- called also white hake.

   Squirrel hawk (Zool.), any rough-legged hawk; especially,
      the California species Archibuteo ferrugineus.

   Squirrel monkey. (Zool.)
      (a) Any one of several species of small, soft-haired South
          American monkeys of the genus Callithrix. They are
          noted for their graceful form and agility. See
          Teetee.
      (b) A marmoset.

   Squirrel petaurus (Zool.), a flying phalanger of Australia.
      See Phalanger, Petaurist, and Flying phalanger under
      Flying.

   Squirrel shrew (Zool.), any one of several species of East
      Indian and Asiatic insectivores of the genus Tupaia.
      They are allied to the shrews, but have a bushy tail, like
      that of a squirrel.

   Squirrel-tail grass (Bot.), a grass (Hordeum jubatum)
      found in salt marshes and along the Great Lakes, having a
      dense spike beset with long awns.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Sciurus niger
    n 1: exceptionally large arboreal squirrel of eastern United
         States [syn: fox squirrel, eastern fox squirrel,
         Sciurus niger]