1. Made dirty or foul
   "breathing air fouled and darkened with factory soot";
   - befouled
    
2. (nautical) not having freedom of motion due to collision or entanglement; entangled
   "with its sails fouled";
   - afoul, foul

1. Commit a foul; break the rules
   "The defender fouled the striker in the penalty area"
    
2. Make unclean
   "foul the water"
    
3. Spoil, spot, stain, or pollute
   "The townspeople fouled the river by emptying raw sewage into it";
   - befoul, defile, maculate [literary]
    
4. Make impure in a bad way; make something harmful, especially by the addition of some unwanted substance
   "The industrial wastes fouled the lake";
   - pollute, contaminate
    
5. Become soiled and dirty
   "The white shirt fouled quickly in the muddy conditions"
    
6. Become or cause to become obstructed
   "The leaves foul our drains in the Fall";
   - clog, choke off, clog up, back up, congest, choke
    
7. (baseball) hit a foul ball
   "He fouled off three pitches before striking out"

See also: dirty, soiled, tangled, unclean

Type of: alter, attaint [archaic], begrime, bemire [archaic], block, change, close up, colly [archaic], dirty, disgrace, dishonor [US], dishonour [Brit, Cdn], grime, hit, impede, jam, modify, obstruct, obturate, occlude, play, shame, soil

Encyclopedia: Foul