Definition of transom

• n. - A horizontal crossbar in a window, over a door, or between a door and a window above it. Transom is the horizontal, as mullion is the vertical, bar across an opening. See Illust. of Mullion.
• n. - One of the principal transverse timbers of the stern, bolted to the sternpost and giving shape to the stern structure; -- called also transsummer.
• n. - The piece of wood or iron connecting the cheeks of some gun carriages.
• n. - The vane of a cross-staff.
• n. - One of the crossbeams connecting the side frames of a truck with each other.