Wapiti, large deer of North America, closely related to the red deer, second only to the moose in size. It is grey-brown with a whitish rump and dark, brown-black legs, head and neck; its antlers may reach a span of 1.5m. In the U.S.A. it is commonly known as elk. Height: to 1.5m; length: to 2.5m. Family Cervidae; species Cervus canadensis.