WordNet (r) 3.0 (2006):

touch screen
    n 1: a computer display that enables the user to interact with
         the computer by touching areas on the screen [syn: touch
         screen, touchscreen]

The Free On-line Dictionary of Computing (30 December 2018):

touch screen

    An input device that allows user to interact with
   computer by touching the display screen.

   Often this uses beams of infrared light that are projected
   across the screen surface.  Interrupting the beams generates
   an electronic signal identifying the location of the screen.
   Software interprets the signal and performs the required
   operation.

   (1995-04-13)