Prudie would prefer we not use the term "butt" to describe the derrière, but substitute "keister," "tushie," "rear-end," or some other synonym. Let's not forget "gluteus maximus," "backside" (my personal favorite), tuches (loan-word from Yiddish), and "rump."

It's a shame, really, because all the word "butt" means is the end of something (e.g., the "butt of a joke" is a punchline, a "butt joint" in carpentry is formed by joining the end of one piece of wood to another). So as far as the the root meaning of the word, the word "butt" itself is no worse than "rear end" in an etymological sense.

On the other hand, I admit that the usage of the word butt has coarsened over time in this culture, and I do hear it used more often by my kids and my kids' friends, and I, too, am not wild about it because when I was growing up, "butt" was not quite a curse-word, but it was definitely considered impolite and usually drew a reprimand from an adult.

To me, it's all in the way that you use it, but there's nothing inherently wrong with the word butt itself. It's a matter of usage and tone.