WordNet (r) 3.0 (2006):

frame buffer
    n 1: (computer science) a buffer that stores the contents of an
         image pixel by pixel

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

frame buffer

    Part of a video system in which an image is
   stored, pixel by pixel and which is used to refresh a
   raster image.  The term "video memory" suggests a fairly
   static display whereas a frame buffer holds one frame from a
   sequence of frames forming a moving image.

   Frame buffers are found in frame grabbers and time base
   correction systems, for example.

   (1997-10-03)