"Richard Stallman"n:http://www.stallman.org gives his explanation of what "hacking" is. I think I agree with him:
"Playfully doing something difficult, whether useful or not, that is hacking."
That's the definition people who hack like. To many people "hacking" is what you do when you "break security to gain access to a system". I often use the word "hack" as a ad hoc desperate technical solution. Much like filling a leaking hole in a dam with chewing gum. It stops the leak but just ain't right.