What is the meaning of Transom?

A crosspiece over a door; a lintel.

A horizontal glazing bar in a window.

A transom window.

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

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.

Items that have arrived over the transom.

Source: wiktionary.org