ETYM Probably from Latin transtrum a crossbeam, transom, from trans across. Related to Trestle.
1. A horizontal piece across a window or separating a door from a window over it; SYN. traverse.
2. A window above a door and hinged to a transom; SYN. transom window, fanlight.
Transverse timbers attached to ship's sternpoststructure dividing a window horizontally; horizontal bar.
Horizontal or transverse beam or bar.