Rapidly rhymes with:
intrepidly, stupidly, acidly, advisedly, allegedly, assuredly, avidly, avowedly, belatedly, blessedly, contentedly, decidedly, deservedly, determinedly, doggedly, excitedly, intrepidly, markedly, morbidly, reportedly, ruggedly, solidly, splendidly, stupidly, supposedly, timidly, unashamedly, vividly
Rapidly sounds like:
raptly, rebuttal, repeatedly, reptile, reputedly, robitaille