Building Trades. pieces of sheet metal or the like used to cover and protect certain joints and angles, as where a roof comes in contact with a wall or chimney, especially against leakage.
the act of creating an artificial flood in a conduit or stream, as in a sewer for cleansing it.
Photography, Movies. the process of increasing film speed by exposing undeveloped film briefly to a weak light source before using it or of exposing photographic printing paper to reduce contrast.

Origin of flashing

First recorded in 1775–85; flash + -ing1
Related formsin·ter·flash·ing, nounun·flash·ing, adjective




a brief, sudden burst of bright light: a flash of lightning.
a sudden, brief outburst or display of joy, wit, etc.
a very brief moment; instant: I'll be back in a flash.
Informal. flashlight(def 1).
superficial, meretricious, or vulgar showiness; ostentatious display.
Also called news flash. Journalism. a brief dispatch sent by a wire service, usually transmitting preliminary news of an important story or development.Compare bulletin(def 2).
  1. bright artificial light thrown briefly upon a subject during an exposure.
  2. flash lamp.
  3. flashbulb.
  4. flashtube.
the sudden flame or intense heat produced by a bomb or other explosive device.
a sudden thought, insight, inspiration, or vision.
Slang. rush1(def 26).
  1. a ridge of metal left on a casting by a seam between parts of the mold.
  2. a ridge formed at the edge of a forging or weld where excess metal has been squeezed out.
Poker. a hand containing all five suits in a game played with a five-suit pack.
a device, as a lock or sluice, for confining and releasing water to send a boat down a shallow stream.
the rush of water thus produced.
Obsolete. the cant or jargon of thieves, vagabonds, etc.

verb (used without object)

to break forth into sudden flame or light, especially transiently or intermittently: a buoy flashing in the distance.
to gleam.
to burst suddenly into view or perception: The answer flashed into his mind.
to move like a flash.
to speak or behave with sudden anger, outrage, or the like (often followed by out): to flash out at a stupid remark.
to break into sudden action.
Slang. to open one's clothes and expose the genitals suddenly, and usually briefly, in public.
Slang. to experience the intense effects of a narcotic or stimulant drug.
to dash or splash, as the sea or waves.
Archaic. to make a flash or sudden display.

verb (used with object)

to emit or send forth (fire or light) in sudden flashes.
to cause to flash, as powder by ignition or a sword by waving.
to send forth like a flash.
to communicate instantaneously, as by radio or telegraph.
to make an ostentatious display of: He's forever flashing a large roll of bills.
to display suddenly and briefly: She flashed her ID card at the guard.
to change (water) instantly into steam by pouring or directing onto a hot surface.
to increase the flow of water in (a river, channel, etc.).
Glassmaking and Ceramics.
  1. to coat (plain glass or a glass or ceramic object) with a layer of colored, opalescent, or white glass.
  2. to apply (such a layer).
  3. to color or make (glass) opaque by reheating.
Building Trades. to protect from leakage with flashing.
Cards. to expose (a card) in the process of dealing.
Archaic. to dash or splash (water).


sudden and brief: a flash storm.
showy or ostentatious.
caused by or used as protection against flash: flash injuries; flash clothing.
counterfeit or sham.
belonging to or connected with thieves, vagabonds, etc., or their cant or jargon.
of or relating to followers of boxing, racing, etc.

Origin of flash

1350–1400; Middle English flasshen to sprinkle, splash, earlier flask(i)en; probably phonesthemic in orig.; compare similar expressive words with fl- and -sh
Related formsflash·ing·ly, adverbout·flash, verb (used with object)

Synonyms for flash

1. flare, gleam, glare. 3. twinkling, wink. 18. scintillate. Flash, glance, glint, glitter mean to send forth a sudden gleam (or gleams) of bright light. To flash is to send forth light with a sudden, transient brilliancy: A shooting star flashed briefly. To glance is to emit a brilliant flash of light as a reflection from a smooth surface: Sunlight glanced from the glass windshield. Glint suggests a hard bright gleam of reflected light, as from something polished or burnished: Light glints from silver or from burnished copper. To glitter is to reflect intermittent flashes of light from a hard surface: Ice glitters in the moonlight. 40. flashy, gaudy, tawdry; pretentious, superficial. 42. false, fake.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for flashing

Contemporary Examples of flashing

Historical Examples of flashing

British Dictionary definitions for flashing



a weatherproof material, esp thin sheet metal, used to cover the valleys between the slopes of a roof, the junction between a chimney and a roof, etc



a sudden short blaze of intense light or flamea flash of sunlight
a sudden occurrence or display, esp one suggestive of brilliancea flash of understanding
a very brief space of timeover in a flash
an ostentatious displaya flash of her diamonds
Also called: newsflash a short news announcement concerning a new event
Also called: patch mainly British an insignia or emblem worn on a uniform, vehicle, etc, to identify its military formation
a patch of bright colour on a dark background, such as light marking on an animal
a volatile mixture of inorganic salts used to produce a glaze on bricks or tiles
  1. a sudden rush of water down a river or watercourse
  2. a device, such as a sluice, for producing such a rush
photog informal short for flashlight (def. 2), flash photography
a ridge of thin metal or plastic formed on a moulded object by the extrusion of excess material between dies
Yorkshire and Lancashire dialect a pond, esp one produced as a consequence of subsidence
(modifier) involving, using, or produced by a flash of heat, light, etcflash blindness; flash distillation
flash in the pan a project, person, etc, that enjoys only short-lived success, notoriety, etc


informal ostentatious or vulgar
informal of or relating to gamblers and followers of boxing and racing
sham or counterfeit
informal relating to or characteristic of the criminal underworld
brief and rapidflash freezing


to burst or cause to burst suddenly or intermittently into flame
to emit or reflect or cause to emit or reflect light suddenly or intermittently
(intr) to move very fasthe flashed by on his bicycle
(intr) to come rapidly (into the mind or vision)
(intr; foll by out or up) to appear like a sudden lighthis anger really flashes out at times
  1. to signal or communicate very fastto flash a message
  2. to signal by use of a light, such as car headlights
(tr) informal to display ostentatiouslyto flash money around
(tr) informal to show suddenly and briefly
(intr) British slang to expose oneself indecently
(tr) to cover (a roof) with flashing
to send a sudden rush of water down (a river, etc), or to carry (a vessel) down by this method
(in the making of glass) to coat (glass) with a thin layer of glass of a different colour
(tr) to subject to a brief pulse of heat or radiation
(tr) to change (a liquid) to a gas by causing it to hit a hot surface
obsolete to splash or dash (water)

Word Origin for flash

C14 (in the sense: to rush, as of water): of unknown origin
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 flashing

1570s, of light; present participle adjective from flash (v.).


"indecent exposure," 1896, verbal noun from flash (v.). The meaning "strip of metal used in roofing, etc." is from 1782, earlier simply flash (1570s), but it is of unknown origin and might be an unrelated word.



1560s, from flash (v.); originally of lightning. Meaning "first news report" is from 1857. Meaning "photographic lamp" is from 1913. The comic book character dates to 1940. Flash in the pan (1809) is from old-style guns, where the powder might ignite in the pan but fail to spark the main charge.



late 14c., from flasken (c.1300) "to dash or splash" (as water), probably imitative. Related: Flashed; flashing. Sense of "give off a sudden burst of light or flame" is 1540s. Flash flood is from 1940. Flash card is from 1923. Flash cube (remember those?) is from 1965.

Online Etymology Dictionary, © 2010 Douglas Harper

Idioms and Phrases with flashing


In addition to the idiom beginning with flash

  • flash in the pan

also see:

  • in a flash
  • quick as a wink (flash)
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.