pixmap
(Contraction of "pixel map"). A 3 dimensional {array} of bits
corresponding to a 2 dimensional array of {pixel}s. 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].