Source : Webster's Revised Unabridged Dictionary (1913)

Flash \Flash\, v. i. [imp. & p. p. {Flashed}; 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.

   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.

            Names which have flashed and thundered as the watch
            words of unnumbered struggles.        --Talfourd.

            The object is made to flash upon the eye of the
            mind.                                 --M. Arnold.

            A thought flashed through me, which I clothed in
            act.                                  --Tennyson.

   3. To burst forth like a sudden flame; to break out
      violently; to rush hastily.

            Every hour He flashes into one gross crime or other.
                                                  --Shak.

   {To flash in the pan}, to fail of success. [Colloq.] See
      under {Flash}, a burst of light. --Bartlett.

   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.

Flashing \Flash"ing\, n.
   1. (Engineering) The creation of an artifical flood by the
      sudden letting in of a body of water; -- called also
      {flushing}.

   2. (Arch.) Pieces of metal, built into the joints of a wall,
      so as to lap over the edge of the gutters or to cover the
      edge of the roofing; also, similar pieces used to cover
      the valleys of roofs of slate, shingles, or the like. By
      extension, the metal covering of ridges and hips of roofs;
      also, in the United States, the protecting of angles and
      breaks in walls of frame houses with waterproof material,
      tarred paper, or the like. Cf. {Filleting}.

   3. (Glass Making)
      (a) The reheating of an article at the furnace aperture
          during manufacture to restore its plastic condition;
          esp., the reheating of a globe of crown glass to allow
          it to assume a flat shape as it is rotated.
      (b) A mode of covering transparent white glass with a film
          of colored glass. --Knight.

   {Flashing point} (Chem.), that degree of temperature at which
      a volatile oil gives off vapor in sufficient quantity to
      burn, or flash, on the approach of a flame, used as a test
      of the comparative safety of oils, esp. kerosene; a
      flashing point of 100[deg] F. is regarded as a fairly safe
      standard. The burning point of the oil is usually from ten
      to thirty degree above the flashing point of its vapor.

Source : WordNet®

flashing
     adj : emitting light in sudden short or intermittent bursts;
           "flashing lightning and roaring thunder"
     n 1: a short vivid experience; "a flash of emotion swept over
          him"; "the flashings of pain were a warning" [syn: {flash}]
     2: sheet metal shaped and attached to a roof for strength and
        weatherproofing