According to wikipedia, the liberal arts were traditionally those subjects which were considered essential for free citizens to study. Today they include such subjects as History, Music, Literature, Science, Maths and Psychology.
However, most people seem to consider them to be the "fluffy" subjects, ones that are "useless" or just for people who want to skive a degree. Under this banner people include things like History, English Literature and Art.
I think those people need to get off their high horses. Oh, what's that, you've got a Physics degree? Well, that's fantastic but don't go around thinking it's much better than a History degree, a History degree takes as much if not more effort.