What constitutes a bite? Breaking of skin? Vicious intent? Nipping in Play?

I don't think I've been actually bitten in what constitutes biting in my eyes. I've been nailed a couple of times accidently by Maddie, when she was going for Oz. Stuck my hand in at the wrong time between'em and being blind, she got me vs him. Smarted, but no skin was broken. But that's about the closest to an actual bite, I've ever been by any breed.

edited to add: My cousin's Aussie nipped at me, when I went to pet it once. But I wouldn't classify it as a bite either. More a warning.

Par...