flash 
(flăsh)
(flăsh)v. flashed, flash·ing, flash·es
v.intr.
1. To burst forth into or as if into flame.
2. To give off light or be lighted in sudden or intermittent bursts.
3. To appear or occur suddenly: The image flashed onto the screen.
4. To move or proceed rapidly: The cars flashed by.
5. To hang up a phone line momentarily, as when using call waiting.
6. Slang To think of or remember something suddenly: flashed on that time we got caught in the storm.
7. Slang To expose oneself in an indecent manner.
v.tr.
1.
a. To cause (light) to appear suddenly or in intermittent bursts.
b. To cause to burst into flame.
c. To reflect (light).
d. To cause to reflect light from (a surface).
2. To make known or signal by flashing lights.
3. To communicate or display at great speed: flashed the news to the world capitals.
4. To exhibit briefly.
5. To hang up (a phone line) momentarily, as when using call waiting.
6. To display ostentatiously; flaunt.
7. To fill suddenly with water.
8. To cover with a thin protective layer.
n.
1. A sudden, brief, intense display of light.
2. A sudden perception: a flash of insight.
3. A split second; an instant: I'll be on my way in a flash.
4. A brief news dispatch or transmission.
5. Slang Gaudy or ostentatious display: "The antique flash and trash of an older southern California have given way to a sleeker age of cultural hip" (Newsweek).
6. A flashlight.
7.
a. Instantaneous illumination for photography: photograph by flash.
b. A device, such as a flashbulb, flashgun, or flash lamp, used to produce such illumination.
8. Slang The pleasurable sensation that accompanies the use of a drug; a rush.
9. Archaic The language or cant of thieves, tramps, or underworld figures.
adj.
Phrasal Verb: 1. Happening suddenly or very quickly: flash freezing.
2. Slang Ostentatious; showy: a flash car.
3. Of or relating to figures of quarterly economic growth released by the government and subject to later revision.
4. Of or relating to photography using instantaneous illumination.
5. Computers Of or relating to flash memory.
6. Archaic Of or relating to thieves, swindlers, and underworld figures.
flash back
Idiom: 1. To experience a psychological flashback: She suddenly flashed back to the moment when the car hit her.
2. To employ a flashback as a narrative device: In the second chapter, the book flashes back to the protagonist's childhood.
flash in the pan
One that promises great success but fails.
[Middle English flashen, to splash, variant of flasken, of imitative origin.]
Synonyms: flash, gleam, glint, sparkle, glitter, glisten, glimmer, twinkle, scintillate
These verbs mean to send forth light. Flash refers to a sudden and brilliant but short-lived outburst of light: A bolt of lightning flashed across the horizon. Gleam implies a transient or subdued light that often appears against a dark background: "The light gleams an instant, then it's night once more" (Samuel Beckett).
Glint applies to briefly gleaming or flashing light: "the fountain's silver-painted swan glinted in the moonlight" (Kate Wheeler).
Sparkle suggests a rapid succession of little flashes of high brilliance (crystal glasses sparkling in the candlelight), and glitter, a similar succession of even greater intensity (jewels glittering in the display case). To glisten is to shine with a sparkling luster: The snow glistened in the dawn light. Glimmer refers to faint, fleeting light: "On the French coast the light / Gleams, and is gone; the cliffs of England stand, / Glimmering and vast, out in the tranquil bay" (Matthew Arnold).
To twinkle is to shine with quick, intermittent flashes or gleams: "a few stars, twinkling faintly in the deep blue of the night sky" (Hugh Walpole).
Scintillate is applied to what flashes as if emitting sparks in a continuous stream: "a dense, hoary mist of ammonium chloride ... depositing minute scintillating crystals on the windowpanes" (Primo Levi). See Also Synonyms at moment.
These verbs mean to send forth light. Flash refers to a sudden and brilliant but short-lived outburst of light: A bolt of lightning flashed across the horizon. Gleam implies a transient or subdued light that often appears against a dark background: "The light gleams an instant, then it's night once more" (Samuel Beckett).
Glint applies to briefly gleaming or flashing light: "the fountain's silver-painted swan glinted in the moonlight" (Kate Wheeler).
Sparkle suggests a rapid succession of little flashes of high brilliance (crystal glasses sparkling in the candlelight), and glitter, a similar succession of even greater intensity (jewels glittering in the display case). To glisten is to shine with a sparkling luster: The snow glistened in the dawn light. Glimmer refers to faint, fleeting light: "On the French coast the light / Gleams, and is gone; the cliffs of England stand, / Glimmering and vast, out in the tranquil bay" (Matthew Arnold).
To twinkle is to shine with quick, intermittent flashes or gleams: "a few stars, twinkling faintly in the deep blue of the night sky" (Hugh Walpole).
Scintillate is applied to what flashes as if emitting sparks in a continuous stream: "a dense, hoary mist of ammonium chloride ... depositing minute scintillating crystals on the windowpanes" (Primo Levi). See Also Synonyms at moment.