"The word hack doesn't really have 69 different meanings," according to MIT hacker Phil Agre. "In fact, hack has only one meaning, an extremely subtle and profound one which defies articulation. Which connotation is implied by a given use of the word depends in similarly profound ways on the context. Similar remarks apply to a couple of other hacker words, most notably random."
Hacking might be characterized as 'an appropriate application of ingenuity'. Whether the result is a quick-and-dirty patchwork job or a carefully crafted work of art, you have to admire the cleverness that went into it.
An important secondary meaning of hack is 'a creative practical joke'. This kind of hack is easier to explain to non-hackers than the programming kind. Of course, some hacks have both natures.