Path of a baseball pop-up

ARC

["Think about the shape a tossed ball makes in the air."]

The clue "Path of a baseball pop-up" leads to the answer "ARC" through a straightforward description of the movement of a baseball. A "pop-up" in baseball is a type of hit where the ball goes high into the air and typically comes straight back down. The path that the ball takes as it goes up and then comes down forms an arc. An "arc" is a curved path or trajectory, which is exactly what the ball follows when it is hit as a pop-up. Therefore, the word "ARC" accurately describes the path of a baseball pop-up.