It's a noun. It's a verb. It's an adjective. It's a buffalo. The plural of buffalo is--- you guessed it-- BUFFALO and if you are a language afficionado who has not seen the video below that explains it all, you are in for a treat.
Makes me wonder how anybody ever learns English, and makes me grateful to be a native speaker of the language that seems simple but is really ooooooh sooooooo complicated. The grammar is insane. I mean, if you have one mouse and two mice, why not one blouse and two blice? But, as we all know, the plural of blouse is blouses. What's a foreigner to do?
Famously, Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo is a grammatically valid English sentence. Check out the details on Wikipedia if you don't believe me. And my hat is off to all the people all over the world who are not buffaloed by the grammatical intricacies of English.
What a language :-)