Bison \Bi"son\ (b[imac]"s[o^]n; 277), n. [L. bison, Gr. bi`swn, a wild ox; akin to OHG. wisunt, wisant, G. wisent, AS. wesend, Icel. v[=i]sundr: cf. F. bison.]

(Zo["o]l.)
   (a) The aurochs or European bison.
   (b) The American bison buffalo (Bison Americanus), a large, gregarious bovine quadruped with shaggy mane and short black horns, which formerly roamed in herds over most of the temperate portion of North America, but is now restricted to very limited districts in the region of the Rocky Mountains, and is rapidly decreasing in numbers.

Source: Webster's Revised Unabridged Dictionary (1913)