The Collaborative International Dictionary of English v.0.48:

Flash \Flash\ (fl[a^]sh), v. i. [imp. & p. p. Flashed
   (fl[a^]sht); p. pr. & vb. n. Flashing.] [Cf. OE. flaskien,
   vlaskien to pour, sprinkle, dial. Sw. flasa to blaze, E.
   flush, flare.]
   1. To burst or break forth with a sudden and transient flood
      of flame and light; as, the lighting flashes vividly; the
      powder flashed.
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   2. To break forth, as a sudden flood of light; to burst
      instantly and brightly on the sight; to show a momentary
      brilliancy; to come or pass like a flash.
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            Names which have flashed and thundered as the watch
            words of unnumbered struggles.        --Talfourd.
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            The object is made to flash upon the eye of the
            mind.                                 --M. Arnold.
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            A thought flashed through me, which I clothed in
            act.                                  --Tennyson.
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   3. To burst forth like a sudden flame; to break out
      violently; to rush hastily.
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            Every hour
            He flashes into one gross crime or other. --Shak.
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   flash in the pan, a failure or a poor performance,
      especially after a normal or auspicious start; also, a
      person whose initial performance appears augur success but
      who fails to achieve anything notable. From 4th pan, n.,
      sense 3 -- part of a flintlock. Occasionally, the powder
      in the pan of a flintlock would flash without conveying
      the fire to the charge, and the ball would fail to be
      discharged. Thus, a good or even spectacular beginning
      that eventually achieves little came to be called a flash
      in the pan.

   To flash in the pan, to fail of success, especially after a
      normal or auspicious start. [Colloq.] See under Flash, a
      burst of light. --Bartlett.
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   Syn: Flash, Glitter, Gleam, Glisten, Glister.

   Usage: Flash differs from glitter and gleam, denoting a flood
          or wide extent of light. The latter words may express
          the issuing of light from a small object, or from a
          pencil of rays. Flash differs from other words, also,
          in denoting suddenness of appearance and
          disappearance. Flashing differs from exploding or
          disploding in not being accompanied with a loud
          report. To glisten, or glister, is to shine with a
          soft and fitful luster, as eyes suffused with tears,
          or flowers wet with dew.
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