pixmap

from The Free On-line Dictionary of Computing (8 July 2008)

pixmap

   (Contraction of "pixel map").  A 3 dimensional {array} of bits
   corresponding to a 2 dimensional array of {pixels}.  It is
   used, for example, in the {X Window System} to describe a
   memory region where graphics can be drawn without affecting
   the screen.  Typically this is used for the efficient handling
   of {expose} events, {icon} images or for animation.  Compare
   {bitmap}.

   [Xlib Guide].