The Collaborative International Dictionary of English v.0.48:

Pronghorn \Prong"horn`\, n. (Zool.)
   An American antelope (Antilocapra Americana), native of the
   plain near the Rocky Mountains. The upper parts are mostly
   yellowish brown; the under parts, the sides of the head and
   throat, and the buttocks, are white. The horny sheath of the
   horns is shed annually. Called also cabr['e]e, cabut,
   prongbuck, and pronghorned antelope.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Antelope \An"te*lope\ ([a^]n"t[-e]*l[=o]p), n. [OF. antelop, F.
   antilope, from Gr. 'anqo`lops, -lopos, Eustathius,
   "Hexa["e]m.," p. 36, the origin of which is unknown.] (Zool.)
   One of a group of ruminant quadrupeds, intermediate between
   the deer and the goat. The horns are usually annulated, or
   ringed. There are many species in Africa and Asia.
   [1913 Webster]

         The antelope and wolf both fierce and fell. --Spenser.
   [1913 Webster]

   Note: The common or bezoar antelope of India is Antilope
         bezoartica. The chamois of the Alps, the gazelle, the
         addax, and the eland are other species. See Gazelle.
         The pronghorn antelope (Antilocapra Americana) is
         found in the Rocky Mountains. See Pronghorn.
         [1913 Webster]

WordNet (r) 3.0 (2006):

Antilocapra americana
    n 1: fleet antelope-like ruminant of western North American
         plains with small branched horns [syn: pronghorn,
         prongbuck, pronghorn antelope, American antelope,
         Antilocapra americana]