And it's codswallop to boot. "Dirty blood." Why, there isn't a wizard alive today that's...

Hermione:
He called me a mudblood. Hagrid:
He did not! Harry:
What's a mudblood? Hermione:
It means dirty blood. Mudblood's a really foul name for someone who's muggle born. Someone with non-magic parents. Someone like me. It's not a term one usually hears in civilized conversation. Hagrid:
See the thing is, Harry, there's some wizards, like the Malfoy family, who think they're better than everyone else because they're what people call "pure blood." Harry:
That's horrible! Ron:
[burps up another slug]
It's disgusting. Hagrid:
And it's codswallop to boot. "Dirty blood." Why, there isn't a wizard alive today that's not half-blood or less. More to the point, they've yet to think of a spell that our Hermione can't do. Come 'ere. Don't you think on it, Hermione. Don't you think on it for one minute