I detect traces of what I've heard called "violent agreement" in this thread. What seems to be being confused is why anyone wants a definition. About half the people on this thread seem to object to the idea, and they want to be free to sing anything they like. I don't think anyone disagrees with that, actually, when it outside a context where other people are paying to hear you. But the other half are saying that they want a definition so that before hearing anything or knowing anything about the singer, they can make some sort of prediction of what they might hear. And this is useful because it enables them to decide whether or not to go to a certain club, or buy a CD speculatively and so on. I cannot believe anyone on this thread thinks it a good idea that you can never make such predictions beforehand.