Trackball

n. input device which includes a ball which may be spun in order to move the cursor (Computers)

A trackball is a pointing device consisting of a ball housed in a socket containing sensors to detect rotation of the ball about two axes—like an upside-down  mouse with an exposed protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a cursor. Large tracker balls are common on CAD workstations for easy precision. Before the advent of the touchpad, small trackballs were common on portable computers, where there may be no desk space on which to run a mouse. Some small thumbballs clip onto the side of the keyboard and have integral buttons with the same function as mouse buttons. An early example of the trackball, perhaps the earliest, was employed in the Canadian military's DATAR system.
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Noun
1. an electronic device consisting of a rotatable ball in a housing; used to position the cursor and move images on a computer screen; "a trackball is essentially an upside-down mouse"
(hypernym) electronic device

n. trackball, input device which includes a ball which may be spun in order to move the cursor

n. trackball, input device which includes a ball which may be spun in order to move the cursor (Computers)