bighorn sheep

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

• noun A wild sheep (Ovis canadensis) of the mountains of western North America, having a brownish coat and, in the male, massive curved horns.

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

• noun A North American endangered species of wild sheep, Ovis canadensis.

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

• noun wild sheep of mountainous regions of western North America having massive curled horns