n.
Pronunciation: ' ras-t ə r
Function: noun
Etymology: German, from Latin raster, rastrum rake, from radere to scrape
Date: 1934
: a scan pattern (as of the electron beam in a cathode-ray tube) in which an area is scanned from side to side in lines from top to bottom also : a pattern of closely spaced rows of dots that form an image (as on the cathode-ray tube of a television or computer display)