Mullion

Mullion, a term commonly associated with architectural elements, serves as a vertical divider between sections of a window or screen, or as an ornamental feature. It is also frequently utilized to separate dual doors. In the context of adjacent window units, its main function is to offer sturdy support to the window's glazing while also providing structural reinforcement to an arch or lintel positioned above the window opening. Furthermore, in architectural design, the horizontal elements that separate the top of a door from a window situated above it are referred to as transoms.