Trackball
An input device that looks like an upside-down mouse. The onscreen pointer is moved by the trackball with a thumb or finger. A trackball requires less arm and wrist motion that a regular mouse takes and therefore is often less stressful for the user to use, helping to prevent
RSI. In the picture to the right, is a
Logitech Cordless Trackman Optical and an example of a trackball mouse.
Also see: Mouse, Mouse definitions, Pointing device