Definitions of foul:

• noun:   an act that violates of the rules of a sport
• verb:   become soiled and dirty
• verb:   make unclean

  Example: "Foul the water"

• verb:   spot, stain, or pollute
• verb:   commit a foul; break the rules
• verb:   hit a foul ball
• verb:   make impure
• verb:   become or cause to become obstructed
• adjective:   (of a baseball) not hit between the foul lines
• adjective:   (of a manuscript) defaced with changes

  Example: "Foul (or dirty) copy"

• adjective:   especially of a ship's lines etc

  Example: "With its sails afoul"

• adjective:   disgustingly dirty; filled or smeared with offensive matter

  Example: "A foul pond"

• adjective:   characterized by obscenity

  Example: "Foul language"

• adjective:   thoroughly unpleasant

  Example: "Filthy (or foul or nasty or vile) weather we're having"

• adjective:   violating accepted standards or rules

  Example: "Used foul means to gain power"

• adjective:   offensively malodorous
• adjective:   highly offensive; arousing aversion or disgust