bison
Concise Oxford English Dictionary © 2008 Oxford University Press:
bison /ˈbʌɪs(ə)n/
▶noun (pl. same) a humpbacked shaggy-haired wild ox. [Bison bison (the N. American buffalo) and B. bonasus (Europe, now only Poland).]
– origin ME: from L., ult. of Gmc origin.
'bison' also found in these Oxford entries:

