What is "pronghorned antelope"

Pronghorn \Prong"horn`\, n. (Zo["o]l.) 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.