(Homonym: fowl).
1. Vile or unsavory.
2. (Of a baseball) Not hit between the foul lines.

In a foul manner; so as to be foul.

(In baseball) A ball struck with the bat so that it does not stay between the foul lines on the playing field; SYN. foul ball.

1. To become foul or dirty.
2. To make foul.
3. To spot, stain, or pollute; SYN. befoul, defile, maculate.
4. To commit a foul; break the rules.
5. To hit a foul ball, in baseball.