- foul: spot, stain, or pollute; "The townspeople defiled the river by emptying raw sewage into it"
- (befouled) made dirty or foul; "a building befouled with soot"; "breathing air fouled and darkened with factory soot"
- (befoulment) the state of being polluted
- To make foul; to soil; To entangle or run against so as to impede motion