Some people associate libertarianism with wanting more freedom, therefore anyone who claims to want more freedom, however it is defined, would be a libertarian.
A prominent libertarian blogger many of you have heard of once told me that a libertarian was anyone who hates the State.
My preferred definition of libertarian has always been "Anyone who accepts the primacy of the Non-Aggression Principle in social affairs and who applies this principle in interpreting the acts of other individuals, as well as themselves, in a fully consistent manner, making no excuses or exceptions."
I admit my definition is a bit wordy (surprise?) but I think it is more technical and specific. Sometimes I add as a corollary that acceptance of the NAP implies self-ownership and self-ownership implies private property rights. But I think at a minimum a libertarian is someone who sees the initiation of the use of force by any individual, in any society, at any time to be a criminal act.
I think you can want more freedom without being a consistent advocate of the NAP. Wanting freedom and understanding the NAP are not necessarily dependent ideas.
I think you can hate the State without being a person who consistently applies the NAP to their observations of human action. For example, you could be a common thief and still hate the State. Therefore, I think you can hate the State and still not be a libertarian.
I'm not trying to pick nits here, rather I am trying to wrestle with something important. If I'm going to label myself and be labeled by others as a libertarian, I need to have a clear, consistent and sufficiently restrictive definition of what that word means if I am to understand it myself. If I don't understand it myself I have little chance of communicating it to other people.