"Language is perpetually in a state of flux for it is a living organism which , shifts, changes, and grows in strength as it absorbs in a sponge like manner, many thousands of new elements. At the same time, it also drops words from useage as fashion dictates.

And at the same time language takes words, and then changes and moulds the meaning over time. Sometimes for inexplicable reasons. For instance buxom originally meant an obedient, meek and mild person. So very different to the idea of a buxom lass:)

Next, awful meant a thing or person that that inspired awe in people. It is a long way from its current meaning of something bad, or for instnce, when someone looks terrible.