There are students of linguistic stochastics who will be able to give you a really detailed answer (although, these days, you may not see them on Blurtit). But (as a people) we tend to find words we like the sound of, and then misuse them. "Fabulous" is a good example. Fifty years ago, it meant "Connected with a Fable" (a story with a meaning). Now it means "really good". Another good example is "prevarication" with means "lying" (in the sense of not telling the truth), but now you find "educated" people using it instead of "wasting time". There are thousands of examples out there, perhaps someone should write a dictionary.....