Main Entry: win•dow
Pronunciation: 'win-(")dO
Function: noun
Usage: often attributive
Etymology: Middle English windowe, from Old Norse vindauga, from vindr wind (akin to Old English wind) + auga eye; akin to Old English Eage eye -- more at EYE
1 a : an opening especially in the wall of a building for admission of light and air that is usually closed by casements or sashes containing transparent material (as glass) and capable of being opened and shut b : WINDOWPANE c : a space behind a window of a retail store containing displayed merchandise d : an opening in a partition or wall through which business is conducted <a bank teller's window>
2 : a means of entrance or access; especially : a means of obtaining information <a window on history>
3 : an opening (as a shutter, slot, or valve) that resembles or suggests a window
4 : the transparent panel or opening of a window envelope
5 : the framework (as a shutter or sash with its fittings) that closes a window opening
6 : CHAFF 4
7 : a range of wavelengths in the electromagnetic spectrum to which a planet's atmosphere is transparent
8 a : an interval of time within which a rocket or spacecraft must be launched to accomplish a particular mission b : an interval of time during which certain conditions or an opportunity exists <a window of vulnerability>
9 : an area at the limits of the earth's sensible atmosphere through which a spacecraft must pass for successful reentry
10 : any of the areas into which a computer display may be divided and on which distinctly different types of information are displayed
- win•dow•less /-dO-l&s, -d&-/ adjective
- out the window : out of existence, use, or consideration

Merriam-Webster Online Dictionary