1580s (earlier buffel, 1510s, from French), from Portuguese bufalo "water buffalo," from Medieval Latin bufalus, variant of Latin bubalus "wild ox," from Greek boubalos
Originally the name of a kind of African antelope, later used of a type of domesticated ox in southern Asia and the Mediterranean lands, a word of uncertain origin.
It appears to contain bous "ox, cow" (from PIE root *gwou- "ox, bull, cow"), but this is perhaps a folk-etymology association.
Wrongly applied since 1630s to the American bison.
The second definition is a little more obscure but still utilized daily: "to intimidate or bully". This most likely originates from the first, because of the tendency of oxen to panic or posture.
The third definition, a city in western New York, is completely different in origin, coming from either a portmanteau of French for "beautiful river" (like the Niagra where it is located).
Combined, these three homographs create the longest grammatically correct sentence using only one word:
Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo.
This might make no sense, but it's AMAZING and it means "Oxen from Buffalo, NY who are bullied by other oxen from Buffalo then bully more oxen :)