1580s (earlier buffel, 1510s, from Middle French), from Portuguese bufalo "water buffalo," from Latin bufalus, variant of bubalus "wild ox," from Greek boubalos "buffalo," originally a kind of African antelope, later used of a type of domesticated ox in southern Asia and the Mediterranean lands, perhaps from bous "ox, cow" (see cow, n.). Wrongly applied since 1630s to the American bison. Buffalo gnat is recorded from 1822.

"alarm, overawe," 1900, from buffalo, n.. Probably from the animals' tendency to mass panic. Related: Buffaloed; buffaloing.