foul line

foul line  {n.}

1. Either of two lines separating fair from foul ground in baseball.

Willie hit the ball just inside the foul line for a double.

2. A line across the upper end of a bowling alley across which a bowler must not step.

John bowled a strike but it didn't count because he stepped over the foul line.

3. A line on the floor in front of the basket in basketball, from which foul shots are made.