Nouns

(n)foulan act that violates the rules of a sport

Verbs

(v)foulhit a foul ball
(v)pollute, foul, contaminatemake impure“The industrial wastes polluted the lake”
(v)clog, choke off, clog up, back up, congest, choke, foul, crap upbecome or cause to become obstructed“The leaves clog our drains in the Fall”, “The water pipe is backed up”
(v)foulcommit a foul; break the rules
(v)foul, befoul, defile, maculatespot, stain, or pollute“The townspeople defiled the river by emptying raw sewage into it”
(v)foulmake unclean“foul the water”
(v)foulbecome soiled and dirty

Adjectives

(s)disgusting, disgustful, distasteful, foul, loathly, loathsome, repellent, repellant, repelling, revolting, skanky, wicked, yuckyhighly offensive; arousing aversion or disgust“a disgusting smell”, “distasteful language”, “a loathsome disease”, “the idea of eating meat is repellent to me”, “revolting food”, “a wicked stench”
(s)fetid, foetid, foul, foul-smelling, funky, noisome, smelly, stinking, ill-scentedoffensively malodorous“a foul odor”, “the kitchen smelled really funky”
(s)cheating, dirty, foul, unsporting, unsportsmanlikeviolating accepted standards or rules“a dirty fighter”, “used foul means to gain power”, “a nasty unsporting serve”, “fined for unsportsmanlike behavior”
(a)foul(of a baseball) not hit between the foul lines
(s)dirty, foul, marked-up(of a manuscript) defaced with changes“foul (or dirty) copy”
(s)cruddy, filthy, foul, nasty, smuttycharacterized by obscenity“had a filthy mouth”, “foul language”, “smutty jokes”
(s)filthy, foul, nastydisgustingly dirty; filled or smeared with offensive matter“as filthy as a pigsty”, “a foul pond”, “a nasty pigsty of a room”
(s)afoul, foul, fouledespecially of a ship's lines etc“with its sails afoul”, “a foul anchor”