Muntin
Dividing panes of glass on a window, muntins can be decorative as well as functional
Also known as a grille, a muntin is a thin strip of wood, metal or plastic used to divide window panes into segmented areas. In many modern metal or vinyl double-paned windows, plastic or metal muntins are positioned between two large solid sheets of glass or panes. Older windows feature wood muntins that have an attractive stepped profile that creates an architectural look, in addition to their functioning as pane dividers. Those running uninterrupted vertically are referred to as long muntins; those running horizontally and connecting to the long muntins are referred to as cross muntins.
This illustration shows two long muntins and three cross muntins for each sash.
Muntins can be highly detailed and finished in a variety of ways.
Or muntins can be very simple to create clean lines.