transom.

a horizontal bar across a window or above a door; also a window positioned above a door

Use it for

Words that belong together

• transom window
• glazed transom
• open transom

On the page

Daylight entered through the transom above the door.

Someone had opened the transom to let out the heat.

The stained-glass transom cast blue patches on the floor.

Usage notes

Primary curation section: Architecture. Specify transom window when referring to the glazed opening rather than its crossbar. Plural: transoms.