beam

American  

[beem] / bim /

noun

1. any of various relatively long pieces of metal, wood, stone, etc., manufactured or shaped especially 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. Nautical.

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

   2. the extreme width of a vessel.

   3. the shank of an anchor.

5. Aeronautics. 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. Machinery.

   1. walking beam.

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

   3. 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, Aeronautics. 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. Citizens Band Radio Slang. beam antenna.

17. a gleam; suggestion.

    a beam of hope.

18. a radiant smile.

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

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verb (used with object)

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

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

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

verb (used without object)

1. to emit beams, as of light.

2. to smile radiantly or happily.

idioms

1. fly the beam, (of an aircraft) to be guided by a beam.

2. off the beam,

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

   2. Informal. wrong; incorrect.

      The pollsters were off the beam again for the last presidential election.

3. beam in, to be received under optimum conditions; be heard loud and clear.

   They told me I was really beaming in.

4. on the beam,

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

   2. Nautical. at right angles to the keel.

   3. Informal. proceeding well; correct; exact.

      Their research is right on the beam and the results should be very valuable.

beam British  

/ biːm /

noun

1. a long thick straight-sided piece of wood, metal, concrete, etc, esp one used as a horizontal structural member

2. any rigid member or structure that is loaded transversely

3. the breadth of a ship or boat taken at its widest part, usually amidships

4. a ray or column of light, as from a beacon

5. a broad smile

6. one of the two cylindrical rollers on a loom, one of which holds the warp threads before weaving, the other the finished work

7. the main stem of a deer's antler from which the smaller branches grow

8. the central shaft of a plough to which all the main parts are attached

9. a narrow unidirectional flow of electromagnetic radiation or particles

   a beam of light

   an electron beam

10. the horizontal centrally pivoted bar in a balance

11. informal the width of the hips (esp in the phrase broad in the beam )

12. a fault or grave error greater in oneself than in another person

13. 1. not following a radio beam to maintain a course

    2. informal wrong, mistaken, or irrelevant

14. 1. following a radio beam to maintain a course

    2. nautical opposite the beam of a vessel; abeam

    3. informal correct, relevant, or appropriate

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verb

1. to send out or radiate (rays of light)

2. (tr) to divert or aim (a radio signal or broadcast, light, etc) in a certain direction

   to beam a programme to Tokyo

3. to pass (data, esp business card details, etc) from one hand-held computer to another by means of infrared beams

4. (intr) to smile broadly with pleasure or satisfaction

beam More Idioms  

1. see broad in the beam; off the beam.

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Related Words

See gleam. See shine ¹.

Other Word Forms

• beamed
  adjective
• beaming
  adjective
• beamless
  adjective
• beamlike
  adjective
• beamy
  adjective
• outbeam
  verb (used with object)
• unbeamed
  adjective
• underbeam
  noun

Etymology

Origin of beam

First recorded before 900; Middle English beem, Old English bēam “tree, post, ray of light”; cognate with Old Frisian bām, Old Saxon bōm, Dutch boom, Old High German boum ( German Baum ), Gothic bagms, Old Norse bathmr tree; the identity of the consonant which has assimilated itself to the following m is unclear, as is the original root; perhaps unattested Germanic bagmaz, from unattested bargmaz, from unattested Indo-European bhorǵh-mos “growth”; see barrow ²

Explanation

A beam is a long board that's used to hold up a roof or doorway. The beams in your kitchen ceiling help support the upstairs floor just above it. In construction, beams are made of wood or metal and are used to frame a building and provide structure. In gymnastics, a beam is used for balancing and doing tricks on. If someone comments that you're getting "broad in the beam," they're disparaging the width of your body, especially your hips. In Old English, a beam first meant a tree, and later a rafter or a ship's timber.

Example Sentences

A beam of light illuminated almost an entire block.

From The Wall Street Journal • May 7, 2026

Equipment mounted below the waterline of a boat emits a fan‑shaped beam of sound waves ahead of the craft.

From The Wall Street Journal • May 5, 2026

The Dean Heritage Centre is home to beam engines and cider presses, and a detailed display charting the history of the areas iconic free miners.

From BBC • May 1, 2026

The breakthrough relied on producing a highly controlled positronium beam.

From Science Daily • Apr. 28, 2026

The beam shuddered when Jake jumped because he heard a shrieking sound behind him.

From "The Smartest Kid in the Universe" by Chris Grabenstein

Related Words

• girder
• joist
• piling
• pillar
• plank
• pole
• shaft
• sill
• timber