What is the meaning of foul?

noun

• An act that violates the rules of a sport.

verb

• Hit a foul ball.
• Make impure.
  • usage: "The industrial wastes polluted the lake"
  • synonyms: pollute, contaminate
• Become or cause to become obstructed.
  • usage: "The leaves clog our drains in the Fall"; "The water pipe is backed up"
  • synonyms: clog, choke off, clog up, back up, congest, choke
• Commit a foul; break the rules.
• Spot, stain, or pollute.
  • usage: "The townspeople defiled the river by emptying raw sewage into it"
  • synonyms: befoul, defile, maculate
• Make unclean.
  • usage: "foul the water"
• Become soiled and dirty.

adjective

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