window
window (wĭnʹdō) noun
1. a. An opening constructed in a wall or roof that functions to admit light or air to an enclosure and is often framed and spanned with glass mounted to permit opening and closing. b. A framework enclosing a pane of glass for such an opening; a sash. c. A pane of glass or similar material enclosed in such a framework.
2. a. An opening that resembles a window in function or appearance. b. The transparent panel on a window envelope.
3. The area or space immediately behind a window, especially at the front of a shop.
4. A means of access or observation: St. Petersburg was Peter the Great's window onto the Baltic.
5. An interval of time during which an activity can or must take place: a brief window of opportunity for a space mission; a window of vulnerability during which the air force was subject to attack.
6. Strips of foil dropped from an aircraft to confuse enemy radar; chaff.
7. A range of electromagnetic frequencies that pass unobstructed through a planetary atmosphere.
8. Computer Science. A small area on a screen in which a file or a part of a file can be displayed.
9. Aerospace. a. A launch window. b. An area at the outer limits of the earth's atmosphere through which a spacecraft must pass in order to return safely.
[Middle English, from Old Norse vindauga : vindr, air, wind + auga, eye.]
Word History: The word window conceals a poetic image that is not at all transparent. Our word comes to us from the Scandinavian invaders and settlers of England in the early Middle Ages. Although we have no record of the exact word they gave us, it was related to Old Norse vindauga,"window," a compound made up of vindr,"wind," and auga,"eye," reflecting the fact that at one time windows contained no glass. In our time we have taken window, which has been recorded in the language for almost 800 years, in a figurative direction with phrases such as launch window, weather window, and window of opportunity or vulnerability. Rockets and missiles now travel through the "wind's eye."