Definition of window bar in English:

window bar

noun

  • 1A bar, or each of a number of bars, fixed over a window, chiefly to prevent occupants from falling out or intruders from gaining access.

  • 2A bar used to secure shutters when closed.

  • 3A bar dividing panes of glass in a window; a muntin; a mullion.

Origin

Early 17th century; earliest use found in Simon Sturtevant (fl. 1612).