The Collaborative International Dictionary of English v.0.48:

Flicker \Flick"er\ (fl[i^]k"[~e]r), v. i. [imp. & p. p.
   Flickered (fl[i^]k"[~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.
      [1913 Webster]

            And flickering on her nest made short essays to
            sing.                                 --Dryden.
      [1913 Webster]

   2. To waver unsteadily, like a flame in a current of air, or
      when about to expire; as, the flickering light.
      [1913 Webster]

            The shadows flicker to fro.           --Tennyson.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Flicker \Flick"er\, n.
   1. The act of wavering or of fluttering; fluctuation; sudden
      and brief increase of brightness; as, the last flicker of
      the dying flame.
      [1913 Webster]

   2. (Zool.) The golden-winged woodpecker (Colaptes aurutus);
      -- so called from its spring note. Called also
      yellow-hammer, high-holder, pigeon woodpecker, and
      yucca.
      [1913 Webster]

            The cackle of the flicker among the oaks.
                                                  --Thoureau.
      [1913 Webster]

WordNet (r) 3.0 (2006):

flicker
    n 1: a momentary flash of light [syn: flicker, spark,
         glint]
    2: North American woodpecker
    3: the act of moving back and forth [syn: waver, flutter,
       flicker]
    v 1: move back and forth very rapidly; "the candle flickered"
         [syn: flicker, waver, flitter, flutter, quiver]
    2: shine unsteadily; "The candle flickered" [syn: flicker,
       flick]
    3: flash intermittently; "The lights flicked on and off" [syn:
       flicker, flick]

Moby Thesaurus II by Grady Ward, 1.0:

184 Moby Thesaurus words for "flicker":
   3-D, Cinemascope, Cinerama, Technicolor, Western, animated cartoon,
   backfire, bake, balefire, be in heat, beacon, beacon fire, beat,
   beating, bicker, black-and-white film, blaze, blink, bloom, boil,
   bonfire, broil, burn, burning ghat, campfire, cartoon,
   cheerful fire, chiller, choke, cinema, color film, combust,
   combustion, conflagration, cook, corposant, coruscate, cozy fire,
   crackling fire, creepie, crematory, dance, dancing, death fire,
   dint, documentary, documentary film, educational film, feature,
   fen fire, film, fire, flame, flame up, flap, flare, flare up,
   flash, flashing point, flick, flickering, flickering flame,
   flickering light, flip, flit, flitter, flop, fluctuate, flush,
   flutter, fluttering, forest fire, fox fire, fry, funeral pyre,
   gasp, glance, glancing light, glare, gleam, glimmer, glimmering,
   glint, glitter, glow, go pitapat, gutter, hint, horror picture,
   horse opera, hover, ignis fatuus, ignition, incandesce, ingle,
   lambency, lambent flame, light show, marshfire, motion picture,
   motion-picture show, movie, moving picture, newsreel, nudie,
   open fire, oscillate, palpitate, palpitation, pant, parch,
   photodrama, photoplay, picture, picture show, pitapat,
   pitter-patter, play, play of light, pornographic film,
   prairie fire, preview, pulse, pyre, quaver, quiver, quivering,
   radiate heat, raging fire, roast, scald, scintilla, scorch,
   sea of flames, seethe, shake, sheet of fire, shimmer,
   shimmer with heat, short, signal beacon, silent, silent film,
   simmer, skin flick, slat, smolder, smother, smudge fire,
   sneak preview, spaghetti Western, spark, sparkle, splutter,
   sputter, steam, stew, stifle, suffocate, suggestion, sweat,
   swelter, swing, talkie, talking picture, three-alarm fire,
   thriller, throb, toast, trace, trailer, tremble, twinkle,
   twinkling, twitter, two-alarm fire, underground film, vestige,
   vibrate, watch fire, wave, waver, wildfire, witch fire