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;
   ground
   
   • he posed her against a background of rolling hills
3. information that is essential to understanding a situation or problem;
   background knowledge
   
   • the embassy filled him in on the background of the incident
4. extraneous signals that can be confused with the phenomenon to be observed or measured;
   background signal
   
   • they got a bad connection and could hardly hear one another over the background signals
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;
   setting, scope
   
   • you can't do that in a university setting
7. (computer science) the area of the screen in graphical user interfaces against which icons and windows appear;
   desktop, screen background
8. scenery hung at back of stage;
   backdrop, backcloth

v.

1. understate the importance or quality of;
   play down, downplay
   
   • he played down his royal ancestry