(1) The transverse measurement of a vessel at its widest part; (2) A term used to indicate direction in relation to a ship, as in "on the beam (abeam)" for something whose direction is at 90 degrees to the vessel; (3) One of the transverse members of a ship's frame on which the decks are laid. In wooden vessels, beams are supported on the ship's sides by right-angled timbers known as knees, and in steel ships by steel brackets or stringers. The depth of a beam is called its moulding, and its width is its siding.