WordNet (r) 3.0 (2006):

die away
    v 1: become less in amount or intensity; "The storm abated";
         "The rain let up after a few hours" [syn: abate, let
         up, slack off, slack, die away]

Moby Thesaurus II by Grady Ward, 1.0:

108 Moby Thesaurus words for "die away":
   abate, ablate, bate, be all over, be annihilated, be consumed,
   be destroyed, be eaten away, be gone, be no more, be wiped out,
   become extinct, become void, blow over, burn out, cease,
   cease to be, cease to exist, consume, consume away, corrode,
   crumble, decline, decrease, deliquesce, dematerialize, depart, die,
   die out, diminish, disappear, dispel, disperse, dissipate,
   dissolve, dive, do a fade-out, drift away, drop, drop off, dwindle,
   ebb, erode, evanesce, evaporate, exit, expire, fade, fade away,
   fade out, fall, fall away, fall off, fizzle, fizzle out, flame out,
   flee, fly, go, go away, go out, have it, have its time, hide,
   languish, lapse, leave no trace, leave the scene, lessen, let up,
   melt, melt away, move away, move off, pass, pass away, pass out,
   perish, peter out, plummet, plunge, pull away, recede, retire,
   retire from sight, retreat, retrocede, run its course, run low,
   run out, sag, shrink, sink, sink away, stand off, subside,
   suffer an eclipse, tail off, vanish, vanish from sight, wane,
   waste, waste away, wear, wear away, wear off, widen the distance,
   withdraw