A pointing device that consists of a ball resting on two rollers at right angles to each other, which translate the ball’s motion into vertical and horizontal movement on the screen. A trackball also typically has one or more buttons to initiate other actions. A trackball’s housing is stationary; its ball is rolled with the hand. See the illustration. Compare mechanical mouse.
input device that carries out the same function as a mouse, but remains stationary. In a trackball the ball controlling the cursor position is operated directly with the fingers.