I've been told that "pit bull" is commonly used to describe at least three different breeds of dog. The one characteristic that they all have in common, from what I've seen, is the massive jaw muscles designed to clamp on and hold on. A (very good) dog trainer told me that it's called a "double hung jaw"; I wouldn't know, but am inclined to trust her since it's her job to know these things. I donno if indestructibility is also a common trait, but it would tend to make sense.

The terrier ;) that won Westminster is a real cutie; he looked like he was having fun. I was amused by the emphasis on him having a "classic head shape", which is to say that his head is shaped like an egg. *giggle*