Large, hoofed mammal of the bovine family. There are two species, both brown. The European bison or wisent Bison bonasus, of which only a few protected herds survive, is about 2 m/7 ft high and weighs up to 1,100 kg/2,500 lb. The North American bison (often known as 'buffalo') Bison bison is slightly smaller, with a heavier mane and more sloping hindquarters. Formerly roaming the prairies in vast numbers, it was almost exterminated in the 19th century, but survives in protected areas. There were about 14,000 bison in North American reserves in 1994.

Crossed with domestic cattle, the latter has produced a hardy hybrid, the 'beefalo', producing a lean carcass on an economical grass diet.