mountain goat

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A goat antelope (Oreamnos americanus) of the northern Rocky Mountains, having curved black horns and a yellowish-white coat and beard.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A sure-footed goat antelope, Oreamnos americanus, of the North American mountains, having black curved horns and a shaggy coat.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun sure-footed mammal of mountainous northwestern North America