n.
Function: intransitive verb
Date: before 12th century
1 : to become or be foul: as a : DECOMPOSE , ROT b : to become encrusted, clogged, or choked with a foreign substance c : to become entangled or come into collision
2 : to commit a violation of the rules in a sport or game
3 : to hit a foul ball
transitive verb
1 : to make foul: as a : to make dirty : POLLUTE b : to tangle or come into collision with c : to encrust with a foreign substance <a ship's bottom foul ed with barnacles> d : OBSTRUCT , BLOCK
2 : DISHONOR , DISCREDIT
3 : to commit a foul against
4 : to hit (a baseball) foul