verb (used with object)

verb (used without object)

to emit beams, as of light.
to smile radiantly or happily.


    beam in, Citizens Band Radio Slang. to be received under optimum conditions; be heard loud and clear: They told me I was really beaming in.
    fly the beam, Radio, Aeronautics. (of an aircraft) to be guided by a beam.
    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.
    on the beam,
    1. on the course indicated by a radio beam, as an airplane.
    2. 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.

Origin of beam

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 Germanic *bagmaz < *bargmaz < Indo-European *bhorǵh-mos growth; see barrow2
Related formsbeam·less, adjectivebeam·like, adjectiveout·beam, verb (used with object)un·beamed, adjectiveun·der·beam, noun

Synonyms for beam

10. See gleam. 20. See shine1. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for on the beam



a long thick straight-sided piece of wood, metal, concrete, etc, esp one used as a horizontal structural member
any rigid member or structure that is loaded transversely
the breadth of a ship or boat taken at its widest part, usually amidships
a ray or column of light, as from a beacon
a broad smile
one of the two cylindrical rollers on a loom, one of which holds the warp threads before weaving, the other the finished work
the main stem of a deer's antler from which the smaller branches grow
the central shaft of a plough to which all the main parts are attached
a narrow unidirectional flow of electromagnetic radiation or particlesa beam of light; an electron beam
the horizontal centrally pivoted bar in a balance
informal the width of the hips (esp in the phrase broad in the beam)
a beam in one's eye a fault or grave error greater in oneself than in another person
off beam or off the beam
  1. not following a radio beam to maintain a course
  2. informalwrong, mistaken, or irrelevant
on the beam
  1. following a radio beam to maintain a course
  2. nauticalopposite the beam of a vessel; abeam
  3. informalcorrect, relevant, or appropriate


to send out or radiate (rays of light)
(tr) to divert or aim (a radio signal or broadcast, light, etc) in a certain directionto beam a programme to Tokyo
to pass (data, esp business card details, etc) from one hand-held computer to another by means of infrared beams
(intr) to smile broadly with pleasure or satisfaction
Derived Formsbeamed, adjectivebeaming, adjective, nounbeamless, adjectivebeamlike, adjectivebeamy, adjective

Word Origin for beam

Old English beam; related to Gothic bagms tree, Old High German boum tree
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for on the beam



"emit rays of light," early 15c., from beam (n.) in the "ray of light" sense. Sense of "to smile radiantly" is from 1804; that of "to direct radio transmissions" is from 1927. Related: Beamed; beaming.



Old English beam originally "living tree," but by late 10c. also "rafter, post, ship's timber," from Proto-Germanic *baumaz (cf. Old Norse baðmr, Old Frisian bam "tree, gallows, beam," Middle Dutch boom, Old High German boum, German Baum "tree," Gothic bagms), perhaps from PIE verb root *bheue- "to grow" (see be). The shift from *-au- to -ea- is regular in Old English.

Meaning "ray of light" developed in Old English, probably because it was used by Bede to render Latin columna lucis, the Biblical "pillar of fire." Nautical sense of "one of the horizontal transverse timbers holding a ship together" is from early 13c., hence "greatest breadth of a ship," and slang broad in the beam "wide-hipped" (of persons). To be on the beam (1941) was originally an aviator's term for "to follow the course indicated by a radio beam."

Online Etymology Dictionary, © 2010 Douglas Harper

Idioms and Phrases with on the beam

on the beam

see under off the beam.


see broad in the beam; off the beam.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.