verb

• (transitive) To cause to shine briefly or intermittently.
  "He flashed the light at the water, trying to see what made the noise."
• (intransitive) To blink; to shine or illuminate intermittently.
  "The light flashed on and off."
• (intransitive) To be visible briefly.
  "The scenery flashed by quickly."
• (transitive) To make visible briefly.
  "A number will be flashed on the screen."

noun

• (colloquial, US) A flashlight; an electric torch.
  "I reached a flash out of my car pocket and went down-grade and looked at the car."
• (figuratively) A sudden and brilliant burst, as of genius or wit.
  "[B]reath his faults ſo quaintly, / That they may ſeeme the taints of liberty; / The flaſh and out-breake of a fiery minde, / A ſauagenes in vnreclaim'd bloud of generall aſſault."
• (figurative, uncountable) Pizzazz, razzle-dazzle.
  "Above all, they hate flash. Just as the English working class has always been, they are fiercely puritanical and abhor all forms of display."
• (British, Cockney) The strips of bright cloth or buttons worn around the collars of market traders.

adj

• (British, Australia and New Zealand, slang) Expensive-looking and demanding attention; stylish; showy.
  "The barber man was small and flash, as barbers mostly are, He wore a strike-your-fancy sash, he smoked a huge cigar;"
• (UK, of a person) Having plenty of ready money.
• (UK, of a person) Liable to show off expensive possessions or money.
  "Bit of a flash git, don't you think?"
• (US, slang) Occurring very rapidly, almost instantaneously.

noun

• (engineering) A reservoir and sluiceway beside a navigable stream, just above a shoal, so that the stream may pour in water as boats pass, and thus bear them over the shoal.