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]

WordNet (r) 3.0 (2006):

flickering
    adj 1: shining unsteadily [syn: flickering, aflicker(p)]

Moby Thesaurus II by Grady Ward, 1.0:

173 Moby Thesaurus words for "flickering":
   ablaze, adrift, afire, aflame, aflicker, afloat, aglow, alight,
   alternating, amorphous, ardent, bickering, blazing, blinking,
   brief, brisk, broken, burning, candent, candescent, capricious,
   careening, catchy, changeable, changeful, choppy, comburent,
   cometary, conflagrant, dancing, desultory, deviable, deviative,
   disconnected, discontinuous, dizzy, eccentric, erratic,
   fast and loose, fickle, fitful, flagrant, flaming, flaring,
   flashing, fleet, flickery, flicky, flighty, flitting, fluctuating,
   fluttering, fluttery, freakish, fuming, giddy, glowing, guttering,
   halting, herky-jerky, heteroclite, ignescent, ignited,
   immethodical, impetuous, impulsive, in a blaze, in a glow,
   in flames, incandescent, inconsistent, inconstant, indecisive,
   infirm, inflamed, intermittent, intermitting, irregular,
   irresolute, irresponsible, jerky, kindled, lambent, live, living,
   lurching, mazy, mercurial, meteoric, moody, nonuniform, on fire,
   patchy, playing, quick, quivering, quivery, rambling, reeking,
   restless, rough, roving, scatterbrained, scintillant,
   scintillating, scrappy, shapeless, shifting, shifty, short,
   short and sweet, short-term, short-termed, shuffling, smoking,
   smoldering, snatchy, sparking, spasmatic, spasmic, spasmodic,
   spastic, speedy, spineless, spluttering, sporadic, spotty,
   sputtering, sputtery, staggering, stroboscopic, swift,
   unaccountable, uncertain, uncontrolled, undependable,
   undisciplined, unequal, uneven, unextinguished, unfixed,
   unmethodical, unmetrical, unpredictable, unquenched, unregular,
   unreliable, unrestrained, unrhythmical, unsettled, unstable,
   unstable as water, unstaid, unsteadfast, unsteady, unsystematic,
   vacillating, vagrant, variable, veering, vicissitudinary,
   vicissitudinous, volatile, wandering, wanton, wavering, wavery,
   wavy, wayward, whimsical, wishy-washy, wobbling, wobbly