Deutsch: Fenster / Español: Ventana / Português: Janela / Français: Fenétre / Italiano: Finestra
A window is a transparent or translucent opening in a wall, door or vehicle that allows the passage of light and, if not closed or sealed, air and sound. Windows are usually glazed or covered in some other transparent or translucent material. Windows are held in place by frames. Many glazed windows may be opened, to allow ventilation, or closed, to exclude inclement weather. Other definition is following.

In an industrial or manufacturing context, a "window" typically refers to a specific period of time during which a particular process or operation can be completed or a specific task can be accomplished. For example, a window of time could be set for a machine to be taken offline for maintenance, or for a product to be delivered to a customer.