A window pane is a single sheet of glass set within a window frame. It lets in light and views while shielding the room from weather and noise. A window may have several panes separated by dividers.
window-pane
Many a doctrine is like a window pane. We see truth through it but it divides us from truth. Kahlil Gibran
Good prose should be transparent, like a window pane. George Orwell
The argument of the broken window pane is the most valuable argument in modern politics. Emmeline Pankhurst
Keep at least one window pane clean to check the weather. Once when I didnt do this I sent the kids off with umbrellas for six weeks straight. Phyllis Diller