noun

• (architecture) The shutter, casement, sash with its fittings, or other framework, which closes a window opening.
• (figurative) A period of time when something is available or possible; a limited opportunity.
  "launch window"
• (figurative) Something that allows one to see through or into something
  "His journal provides a rare window into his otherwise obscure life."
• (graphical user interface) A rectangular area on a computer terminal or screen containing some kind of user interface, displaying output and allowing input, often for a single task in a multitasking system.

verb

• (transitive) To furnish with windows.
• (transitive) To place at or in a window.
  "Wouldst thou be windowed in great Rome and see / Thy master thus with pleach'd arms, bending down / His corrigible neck?"
• (transitive, signal processing) To apply a window function to (a signal).