Transom

Part of speech: noun

Pronunciation: /ˈtɹæn.səm/

Definitions

1. A horizontal beam positioned across the top of a door or window that provides support and stability; an area that can accommodate glass for light penetration or airflow; an important architectural component used in various designs for both aesthetics and function
2. A structural horizontal bar situated above a door frame ; a glass panel set above a door to allow extra light or ventilation
3. The beam running transversely atop a door opening ; a small window fixed above a door to admit light or air

Etymology: The beam that crosses the top of a doorway and the small window set above a door share one name, and the window sense is in fact the later one in the sense that it grew from the beam. Middle English had "traunsom," which likely altered Latin "trānstrum," meaning "crossbeam" or "cross-bench." The Latin word itself came from "trans," meaning "across," and it is a fitting root for a piece of timber laid over an opening from side to side. Over time the word narrowed from the structural member to the object it framed or supported. A transom in the older sense is the horizontal bar, often carved or made of heavy wood, that separates a doorway from the glazing above it. When the space above that bar was filled with glass, the fixed window became known by the same name, which is why a window above a door can still be called a transom today.

Synonyms: crossbeam