One can actually show that any number of "buffalo" greater than 1 is a "valid" sentence. One can construct a simple recursive CFG which models a basic part of English grammar. The word buffalo is both a noun and a verb, which is all that is necessary.
Of course, the human brain can only take so much recursion.
The cat ran.
The cat the dog chased ran.
*The cat the dog the flea bit chased ran.
Chinese and other inflected languages
Chinese is not considered an inflected, or synthetic, language. Latin and Russian are. Some call Chinese an analytic language.
—Ceci n'est pas un seing.
Interesting, zmj. I can see how German is a synthetic language.
I found it interesting that Wikipedia and Language Log each interpreted that "buffalo" sentence differently.
Was does grammatical mean if no one can understand it?
"grammatical" in theoretical linguistics means "generated by the grammar". The grammar is the set of rules that let speakers form and understand sentences. Chomsky argued that the grammar can generate sentences with an infinite number of recursively embedded clauses.
The cat the dog the flea bit chased ran.
The cat the dog the flea the bird caught bit chased ran.
The cat the dog the flea the bird the hawk followed caught bit chased ran.
And so on.
I think Chomsky argued this because he couldn't find a way for the grammar to stop allowing embedding after a certain point. He argued that altho these sorts of sentences are grammatical, they can't be produced or understood because of other, not strictly linguistic factors such as short term memory.
Chomsky maintains that recursion is an essential part of language. Not everyone agrees. Language Log has a rundown of the debate.