window
win·dow
 /ˈwındoʊ/  noun  ,  pl   -dows
  1 [  count  ]
  1 a : an opening in a wall, door, etc., that usually contains a sheet of glass
   She opened a window to let in some air.
   I looked out the window and saw a deer.
  — see also bay window, FRENCH WINDOW, picture window, rose window, storm window
  1 b : a sheet of glass that covers an opening in a building, vehicle, etc.
   He used vinegar and water to wash the windows.
   He accidentally broke a window.
   Can you roll down the car window?
  1 c : a large window at the front of a store where goods are displayed so that they can be seen by people who are walking past
   The windows along 5th Avenue were all decorated for Christmas.
   I saw a beautiful dress in the window.
  1 d : an opening in a wall through which business is conducted
   He sits behind a window and sells movie tickets.
   a ticket window
   a bank teller's window
  2 [  count  ] : a part of something that you can see through
   Make sure the address shows through the window in the envelope.
   A window opened in the fog and we could finally see the ocean.
  3 [  count  ] : an area or box on a computer screen that shows a program that is currently running
   Minimize that window and open a new one.
   Close all the windows and restart the computer.
  4 [  singular  ] : a period of time during which something can happen
   The shuttle's launch has a window of only two days. [=it can only happen within two specific days]
   The window of opportunity [=the time during which there is a chance to do something] has closed/ended.
  a window into/on
   : something that makes it possible to see or understand something clearly
    This knowledge opens a window into your opponent's mind.
    The book gives the reader a window on war.
  go out the window
    informal   : to stop being used or thought about
    By that point in the argument, reason had gone out the window.
  throw (something) out the window
    informal   : to stop using or thinking about (something)
    We can throw that idea out the window.