The precise meaning of the 'Non-Commercial' clause matters only to those who want to violate it. This is my view, at least, and I would add that people looking for precise definitions are looking for loopholes. It's like the definition of 'expensive'. If you have to ask, you probably won't like the answer. Tony karrer, though, argues for precise definitions. "Bottom line is that Creative Commons is failing to really help us. If you have to go and contact each license holder to find out, you are basically in the same boat as with copyright" (Karrer also doesn't need definite articles). But you don't need to go asking to find out. Because, if you're asking about this, you already know the answer. Right?