a Covered with, or containing, extraneous matter which is injurious, noxious, offensive, or obstructive; filthy; dirty; not clean; polluted; nasty; defiled; as, a foul cloth; foul hands; a foul chimney; foul air; a ship's bottom is foul when overgrown with barnacles; a gun becomes foul from repeated firing; a well is foul with polluted water.
a Not favorable; unpropitious; not fair or advantageous; as, a foul wind; a foul road; cloudy or rainy; stormy; not fair; -- said of the weather, sky, etc.
a Not conformed to the established rules and customs of a game, conflict, test, etc.; unfair; dishonest; dishonorable; cheating; as, foul play.
a (nautical) Having freedom of motion interfered with by collision or entanglement; entangled; -- opposed to clear; as, a rope or cable may get foul while paying it out.
a (baseball) Outside of the base lines; in foul territory.
v (transitive|basketball) To make contact with an opposing player in order to gain advantage.
v (transitive|baseball) To hit outside of the baselines.
v (intransitive) To become clogged.
v (intransitive) To become entangled.
v (intransitive|basketball) To commit a foul.
v (intransitive|baseball) To hit a ball outside of the baselines.
n (sports) A breach of the rules of a game, especially one involving inappropriate contact with an opposing player in order to gain an advantage; as, for example, foot-tripping in soccer, or contact of any kind in basketball.
n (bowling) A (usually accidental) contact between a bowler and the lane before the bowler has released the ball.
n (baseball) A foul ball, a ball which has been hit outside of the base lines.