background
     n 1: a person's social heritage: previous experience or training;
          "he is a lawyer with a sports background"
     2: the part of a scene (or picture) that lies behind objects in
        the foreground; "he posed her against a background of
        rolling hills" [syn: {ground}]
     3: information that is essential to understanding a situation
        or problem; "the embassy filled him in on the background
        of the incident" [syn: {background knowledge}]
     4: extraneous signals that can be confused with the phenomenon
        to be observed or measured; "they got a bad connection and
        could hardly hear one another over the background signals"
        [syn: {background signal}]
     5: relatively unimportant or inconspicuous accompanying
        situation; "when the rain came he could hear the sound of
        thunder in the background"
     6: the state of the environment in which a situation exists;
        "you can't do that in a university setting" [syn: {setting},
         {scope}]
     7: (computer science) the area of the screen in graphical user
        interfaces against which icons and windows appear [syn: {desktop},
         {screen background}]
     8: scenery hung at back of stage [syn: {backdrop}, {backcloth}]
     v : understate the importance or quality of; "he played down his
         royal ancestry" [syn: {play down}, {downplay}] [ant: {foreground},
          {foreground}]
Source: WordNet® 2.0

background n.,adj.,vt. [common] To do a task `in background' is to do
   it whenever {foreground} matters are not claiming your undivided
   attention, and `to background' something means to relegate it to a lower
   priority. "For now, we'll just print a list of nodes and links; I'm
   working on the graph-printing problem in background." Note that this
   implies ongoing activity but at a reduced level or in spare time, in
   contrast to mainstream `back burner' (which connotes benign neglect
   until some future resumption of activity). Some people prefer to use the
   term for processing that they have queued up for their unconscious minds
   (a tack that one can often fruitfully take upon encountering an obstacle
   in creative work). Compare {amp off}, {slopsucker}.

   Technically, a task running in background is detached from the
   terminal where it was started (and often running at a lower priority);
   oppose {foreground}. Nowadays this term is primarily associated with
   {{Unix}}, but it appears to have been first used in this sense on
   OS/360.


Source: The Jargon File