an opening in the wall of a building, the side of a vehicle, etc., for the admission of air or light, or both, commonly fitted with a frame in which are set movable sashes containing panes of glass.
2.
such an opening with the frame, sashes, and panes of glass, or any other device, by which it is closed.
3.
the frame, sashes, and panes of glass, or the like, intended to fit such an opening: Finally the builders put in the windows.
4.
a windowpane.
5.
anything likened to a window in appearance or function, as a transparent section in an envelope, displaying the address.
a period of time regarded as highly favorable for initiating or completing something: Investors have a window of perhaps six months before interest rates rise.
a specific area at the outer limits of the earth's atmosphere through which a spacecraft must reenter to arrive safely at its planned destination.
11.
Computers. a section of a display screen that can be created for viewing information from another part of a file or from another file: The split screen feature enables a user to create two or more windows.
early 13c., lit. "wind eye," from O.N. vindauga, from vindr "wind" (see wind (n.)) + auga "eye." Replaced O.E. eagþyrl, lit. "eye-hole," and eagduru, lit. "eye-door." Originally an unglazed hole in a roof, most Germanic languages adopted a version of L. fenestra to describe
the glass version, and English used fenester as a parallel word till mid-16c. Window dressing is first recorded 1790; fig. sense is from 1898. Window seat is attested from 1778. Window-shopping is recorded from 1922. Window of opportunity (1979) is from earlier fig. use in U.S. space program, e.g. launch window (1965).