Wiktionary
n. (context computing English) An input device that enables a user to draw images by hand, as if with a pencil, and import them into a computer system.
Wikipedia
A graphics tablet (also known as a digitizer, drawing tablet, digital drawing tablet, pen tablet, or digital art board) is a computer input device that enables a user to hand-draw images, animations and graphics, with a special pen-like stylus, similar to the way a person draws images with a pencil and paper. These tablets may also be used to capture data or handwritten signatures. It can also be used to trace an image from a piece of paper which is taped or otherwise secured to the tablet surface. Capturing data in this way, by tracing or entering the corners of linear poly-lines or shapes, is called digitizing.
The device consists of a flat surface upon which the user may "draw" or trace an image using the attached stylus, a pen-like drawing apparatus. The image is displayed on the computer monitor, though some graphics tablets now also incorporate an LCD screen for a more realistic or natural experience and usability.
Some tablets are intended as a replacement for the computer mouse as the primary pointing and navigation device for desktop computers.