It's neither concise or well-defined, very similar to Knowledge Management itself. Ray Sims provides a great starting point for defining KM. Forty-three different definitions from various sources. Personally, I could only whittle down my favorite to a half-dozen. I think one of the main distinctions I'd like to see is Information Management versus Knowledge Management. I honestly don't think that is too clear either.
Ray is going to further elaborate through a cloud map and classifications. I'm looking forward to it.