To me this seems unhelpful. I'd say there is no "knowledge"; there's only belief. And if you defined knowledge as "justified true belief" then you couldn't apply the definition in practice in the real world because you don't know when something is true. But that's philosophy for you: fun (for some people) but not useful.
Why deny the word has meaning, just because you can't distill it down to a concise explanation? The meaning of a word can be arbitrarily complex. Knowledge can exist, even if you can't define it, because meaning is not determined by definition. Definitions are simply a mechanism for coordinating understanding, not for demonstrating its existence.
Besides, any argument against the existence of knowledge could be used against belief. Play "taboo" with the subject and don't confine yourself to using ancient terminology to describe the world and these pointless linguistic problems melt away.