WordNet (r) 3.0 (2006):

fluttering
    n 1: the motion made by flapping up and down [syn: flap,
         flapping, flutter, fluttering]

Moby Thesaurus II by Grady Ward, 1.0:

82 Moby Thesaurus words for "fluttering":
   aflicker, agitated, airborne, beating, bickering, birdies,
   blinking, blooping, blurping, bustling, clicking, dance, dancing,
   desultory, distortion, drumming, feedback, fidgety, flashing,
   flicker, flickering, flickering light, flickery, flicky, flitting,
   flutter, fluttery, flying, fretful, fussing, fussy, glancing light,
   gliding, guttering, hissing, hovering, howling, hum, jet-propelled,
   jumpy, lambency, lambent, light show, motorboating, palpitant,
   play, play of light, playing, pounding, quiver, quivering, quivery,
   restless, rocket-propelled, rumble, scratching, shredding,
   spattering, spluttering, sputtering, sputtery, squeals, staccato,
   static, stroboscopic, throbbing, thrumming, thumping, ticking,
   turbulent, unquiet, unsettled, unsteady, volant, volitant,
   wavering, wavery, whistles, winging, woomping, wow, wowwows