A Window

1. An opening, usually covered by one or more panes of clear glass, to allow light and air from outside to enter a building or vehicle.
2. An opening, usually covered by glass, in a shop which allows people to view the shop and its products from outside; a shop window.
3. (architecture) The shutter, casement, sash with its fittings, or other framework, which closes a window opening.
4. A period of time when something is available.
5. Something that allows one to see through or into something
6. A restricted range.
7. (graphical user interface) A rectangular area on a computer terminal or screen containing some kind of user interface, displaying the output of and allowing input for one of a number of simultaneously running computer processes.
8. A figure formed of lines crossing each other.
9. (medicine) The time between first infection and detectability.
10. (military, historical, uncountable) Synonym of chaff (“strips of material intended to confuse radar”)
11. (signal processing)

Visible and Radio Windows:

the Earth’s atmosphere limits what we can actually detect. Ultraviolet and shorter wavelengths are blocked by the atmosphere. Visible light passes through the clear atmosphere (but is blocked by clouds). Most infrared wavelengths are blocked by the atmosphere, but some wavelengths get through. For the most part, radio waves pass through the atmosphere with little absorption. We speak of visible and radio windows in the atmosphere, as well as some narrow windows in the infrared. A window is simply a wavelength range in which the atmosphere is at least partially transparent.