I've seen this definition of balanced tree being thrown around a couple of times:
"A tree with n nodes is said to be balanced if its height is O(lg n)."
Now, I'm guessing there's an abuse here, right? Because the height of a single tree is a particular value, not a function. So, what is it trying to say? Or am I missing something? Also, is there another definition of what a balanced tree is that is a bit clearer?