In baseball, a fastball pitch that breaks toward the low portion of the strike zone and inside or away with the goal of producing a ground ball out.
Also known as a "drop ball", the sinker employs the grip of a two-seam fastball, in which the index and the middle finger are parallel to the two seams on the baseball, and is often released in a downward motion of the wrist, causing the pitch to "sink" closer to the ground. Lateral movement of the fastball is caused by a sidespin, generated when the pitcher rotates the ball outwards somewhat like a screwball. Finger pressure on one of the two seams adds a tilt to the spin of the ball, causing downward sink as the ball moves inside or away from the batter. Sinkers, like two-seam fastballs, are typically a few miles slower than four-seam fastballs, but the movement and sink cause most balls to be hit on the ground.