beam

—beamless, adj. —beamlike, adj.

/beem/, n.

1. any of various relatively long pieces of metal, wood, stone, etc., manufactured or shaped esp. for use as rigid members or parts of structures or machines.

2. Building Trades. a horizontal bearing member, as a joist or lintel.

3. Engineering. a rigid member or structure supported at each end, subject to bending stresses from a direction perpendicular to its length.

4. Naut.

a. a horizontal structural member, usually transverse, for supporting the decks and flats of a vessel.

b. the extreme width of a vessel.

c. the shank of an anchor.

5. Aeron. the direction perpendicular to the plane of symmetry of an aircraft and outward from the side.

6. the widest part.

7. Slang. the measure across both hips or buttocks: broad in the beam.

8. Mach.

a. See walking beam.

b. (in a loom) a roller or cylinder on which the warp is wound before weaving.

c. a similar cylinder on which cloth is wound as it is woven.

9. the crossbar of a balance, from the ends of which the scales or pans are suspended.

10. a ray of light: The sun shed its beams upon the vineyard.

11. a group of nearly parallel rays.

12. Radio, Aeron. a signal transmitted along a narrow course, used to guide pilots through darkness, bad weather, etc.

13. Electronics. a narrow stream of electrons, as that emitted from the electron gun of a cathode ray tube.

14. the angle at which a microphone or loudspeaker functions best.

15. the cone-shaped range of effective use of a microphone or loudspeaker.

16. CB Radio Slang. See beam antenna.

17. a gleam; suggestion: a beam of hope.

18. a radiant smile.

19. the principal stem of the antler of a deer.

20. fly the beam, Radio, Aeron. (of an aircraft) to be guided by a beam.

21. off the beam,

a. not on the course indicated by a radio beam.

b. Informal. wrong; incorrect: The pollsters were off the beam again for the last presidential election.

22. on the beam,

a. on the course indicated by a radio beam, as an airplane.

b. Naut. at right angles to the keel.

c. Informal. proceeding well; correct; exact: Their research is right on the beam and the results should be very valuable.

v.t.

23. to emit in or as in beams or rays.

24. Radio. to transmit (a signal) in a particular direction.

25. Radio and Television. to direct (a program, commercial message, etc.) to a predetermined audience.

v.i.

26. to emit beams, as of light.

27. to smile radiantly or happily.

28. beam in, CB Radio Slang. to be received under optimum conditions; be heard loud and clear: They told me I was really beaming in.

[bef. 900; ME beem, OE beam tree, post, ray of light; c. OFris bam, OS bom, D boom, OHG boum (G Baum), Goth bagms, ON bathmr tree; the identity of the consonant which has assimilated itself to the following m is unclear, as is the original root; perh. Gmc *bagmaz < *bargmaz < IE *bhorgh-mos growth; see BARROW²]

Syn. 10. See gleam. 23. See shine.

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In building construction, a horizontal member spanning an opening and carrying a load.

The load may be a wall above the opening (see post-and-beam system) or it may be a floor or roof. Beams may be of wood, steel or other metals, reinforced or prestressed concrete, plastic, or even brick with steel reinforcement. For weight reduction, metal beams are I-shaped, having a thin vertical web and thicker horizontal flanges where greater stress occurs. A joist is any of a series of small parallel beams supporting a floor or roof. See also girder, spandrel.

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▪ architecture

      in engineering, originally a solid piece of timber, as a beam of a house, a plow, a loom, or a balance. In building construction, a beam is a horizontal member spanning an opening and carrying a load that may be a brick or stone wall above the opening, in which case the beam is often called a lintel (see post-and-lintel system). The load may be a floor or roof in a building, in which case the beam is called a floor joist or a roof joist. In a bridge deck the lightly loaded longitudinal beams are the stringers; the heavier, transverse members are called floor beams.

      Large beams carrying the ends of other beams perpendicular to them are usually called girders (girder). Metal girders may be single rolled pieces or, to permit greater stiffness and longer spans, may be built up in the form of an I by rivetting or welding plates and angles. Concrete girders are also widely used.

      Beams may be of wood, steel or other metals, reinforced or prestressed concrete, plastics, and even brickwork with steel rods in the bond between bricks. For weight reduction, beams of metal are formed as an I or other shape having a thin vertical web and thicker horizontal flanges where most of the strain appears. See also cantilever.

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