Over time I've adopted the "justified true belief" as my definition for knowledge. I'm completely satisfied with it, but, of course, it's just a shortcut to the factual definition.
First, the nature of knowledge is to be knowledge of something. It is a description of something and can never be completely that something: the map is not the territory. Therefore, no absolute knowledge exists; at its very best it's only a belief.
True refers to the correspondence theory of truth. Knowledge is a description of a state of affairs; if the description corresponds the state of affairs (which may include other descriptions), we say that the description is true.
Justified refers to the coherence theory of truth. If a new description is ambiguous or contradictory with other descriptions which our worldview consists of, some of them need to be changed. If the new description is coherent with our existing worldview, it becomes justified by the coherence.
I'm emphasizing that correspondence and coherence are the two necessary dimensions of knowledge.