1. [n]  the act of moving back and forth
2. [n]  North American woodpecker
3. [n]  a momentary flash of light
4. [v]  move back and forth very rapidly, as of a candle
5. [v]  flash intermittently; "The lights flicked on and off"
6. [v]  shine unsteadily; "The candle flickered"

Flicker
Flicker

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1. \Flick"er\ (-[~e]r), v. i. [imp. & p. p. {Flickered}
   (-[~e]rd); p. pr. & vb. n. {Flickering}.] [OE. flikeren,
   flekeren, to flutter, AS. flicerian, flicorian, cf. D.
   flikkeren to sparkle. [root]84. Cf. Flacker.]
   1. To flutter; to flap the wings without flying.
            And flickering on her nest made short essays to
            sing.                                 --Dryden.
   2. To waver unsteadily, like a flame in a current of air, or
      when about to expire; as, the flickering light.
            The shadows flicker to fro.           --Tennyson.
   

2. \Flick"er\, n.
   1. The act of wavering or of fluttering; flucuation; sudden
      and brief increase of brightness; as, the last flicker of
      the dying flame.
   2. (Zo["o]l.) The golden-winged woodpecker ({Colaptes
      aurutus}); -- so called from its spring note. Called also
      {yellow-hammer}, {high-holder}, {pigeon woodpecker}, and
      {yucca}.
            The cackle of the flicker among the oaks.
                                                  --Thoureau.