Beam (bēm), n. [AS. beám beam, post, tree, ray of light; akin to OFries. bām tree, OS. bōm, D. boom, OHG. boum, poum, G. baum, Icel. baðmr, Goth. bagms and Gr. φυ̑μα a growth, φυ̑ναι to become, to be. Cf. L. radius staff, rod, spoke of a wheel, beam or ray, and G. strahl arrow, spoke of a wheel, ray or beam, flash of lightning. √97. See Be; cf. Boom a spar.] 1. Any large piece of timber or iron long in proportion to its thickness, and prepared for use.
2. One of the principal horizontal timbers of a building or ship.
The beams of a vessel are strong pieces of timber stretching across from side to side to support the decks.
Totten.
3. The width of a vessel; as, one vessel is said to have more beam than another.
4. The bar of a balance, from the ends of which the scales are suspended.
The doubtful beam long nods from side to side.
Pope.
5. The principal stem or horn of a stag or other deer, which bears the antlers, or branches.
6. The pole of a carriage. Dryden.
7. A cylinder of wood, making part of a loom, on which weavers wind the warp before weaving; also, the cylinder on which the cloth is rolled, as it is woven; one being called the fore beam, the other the back beam.
8. The straight part or shank of an anchor.
9. The main part of a plow, to which the handles and colter are secured, and to the end of which are attached the oxen or horses that draw it.
10. (Steam Engine) A heavy iron lever having an oscillating motion on a central axis, one end of which is connected with the piston rod from which it receives motion, and the other with the crank of the wheel shaft; — called also working beam or walking beam.
11. A ray or collection of parallel rays emitted from the sun or other luminous body; as, a beam of light, or of heat.
How far that little candle throws his beams!
Shak.
12. Fig.: A ray; a gleam; as, a beam of comfort.
Mercy with her genial beam.
Keble.
13. One of the long feathers in the wing of a hawk; — called also beam feather.
Abaft the beam(Naut.), in an arc of the horizon between a line that crosses the ship at right angles, or in the direction of her beams, and that point of the compass toward which her stern is directed. — Beam center(Mach.), the fulcrum or pin on which the working beam of an engine vibrates. — Beam compass, an instrument consisting of a rod or beam, having sliding sockets that carry steel or pencil points; — used for drawing or describing large circles. — Beam engine, a steam engine having a working beam to transmit power, in distinction from one which has its piston rod attached directly to the crank of the wheel shaft. — Before the beam(Naut.), in an arc of the horizon included between a line that crosses the ship at right angles and that point of the compass toward which the ship steers. — On the beam, in a line with the beams, or at right angles with the keel. — On the weather beam, on the side of a ship which faces the wind. — To be on her beam ends, to incline, as a vessel, so much on one side that her beams approach a vertical position.