mule deer

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A brownish-gray deer (Odocoileus hemionus) of western North America, having long mulelike ears, large branching antlers in the male, and a black-tipped tail. Also called black-tailed deer.

Century Dictionary and Cyclopedia

1. n. The blacktail or black-tailed deer, Cariacus macrotis: so called from the large ears. It is decidedly larger and more stately than the Virginia or white-tailed deer, and is next in size to the wapiti and caribou among the North American Cervidœ. The tail is very short and slim, and mostly white, but with a black brush at the end. The antlers are characteristic, being doubly dichotomous — that is, the beam forks, and each tine forks again; whereas in C. virginianus the beam is curved and all the tines spring from it. The animal is the commonest deer in many wooded and mountainous parts of western North America, but is not found east of the great plains.

Wiktionary

1. n. A deer, found in western North America.

GNU Webster's 1913

1. n. (Zoöl.) a large deer (Cervus macrotis syn. Cariacus macrotis) of the Western United States. The name refers to its long ears.

WordNet 3.0

1. n. long-eared deer of western North America with two-pronged antlers