A general-purpose computer, usually portable, contained in a single panel and using a touch screen as the input device.
A general-purpose computer contained in a single panel. Its distinguishing characteristic is the use of a touch screen as the input device. Modern tablets are operated by fingers (and gestures), with a stylus is an option, whereas earlier tablets required a stylus.
Adapted from:
http://www.pcmag.com/encyclopedia_term/0,2542,t=tablet+computer&i=52520,00.asp
Alternate meaning:
A graphics tablet consists of a flat surface upon which the user may "draw" or trace an image using an attached stylus, a pen-like drawing apparatus.
See: graphics-tablet