1. A horizontal crosspiece across a window or separating a door from a window over it
   "The transom above the door allowed extra light into the room";
   - traverse
    
2. A window above a door that is usually hinged to a horizontal crosspiece over the door
   "The transom window allowed extra light into the hallway";
   - transom window, fanlight

Derived forms: transoms

Type of: crosspiece, window

Encyclopedia: Transom