—adj. 1. foul with, characterized by, or having the nature of filth; disgustingly or completely dirty.
2. vile; vulgar; obscene: filthy language. 3. contemptibly offensive, vile, or objectionable: to treat one's friends in a filthy manner. 4. (of money) abundantly supplied (often fol. by with): They're filthy with money.
—adv. (of money or wealth) very; extremely: They say he's filthy rich.