(architecture) A crosspiece over a door; a lintel.

(architecture) A horizontal dividing bar in a window.

A transom window.

(nautical) Any of several transverse structural members in a ship, especially at the stern; a thwart.

(nautical) The flat or nearly flat stern of a boat or ship.a ship's transom (flat stern)

The horizontal beam on a cross or gallows.

(figurative, usually attributively) Items that have arrived over the transom.