[1] : The Collaborative International Dictionary of English v.0.48

dreadfully \dread"fully\, adv.
   in a dreadful manner; terribly. --dryden.
   1913 webster

[2] : WordNet (r) 2.0

dreadfully
     adv 1: of a dreadful kind; "there was a dreadfully bloody accident
            on the road this morning" syn: awfully, horribly
     2: in a dreadful manner; "as he looks at the mess he has left
        behind he must wonder how the brits so often managed to
        succeed in the kind of situation where he has so dismally
        failed" syn: dismally
see also:
awfully horribly dismally 

[3] : Moby Thesaurus II by Grady Ward, 1.0

112 moby thesaurus words for "dreadfully":
   abominably, agonizingly, alarmingly, appallingly, astoundingly,
   atrociously, awful, awfully, baldly, balefully, banefully, basely,
   bestially, big, bitterly, blatantly, brashly, brutally,
   confoundedly, contemptibly, cruelly, damnably, damned, deadly,
   deathly, despicably, detestably, deucedly, direly, disconcertingly,
   disgustingly, dismayingly, distressingly, dolorously, dreadful,
   egregiously, exceedingly, excessively, excruciatingly,
   exorbitantly, extravagantly, extremely, fearfully, flagrantly,
   forbiddingly, foully, frightfully, fulsomely, ghastly, grievously,
   grimly, grossly, gruesomely, hellishly, hideously, horrendously,
   horribly, horridly, horrifically, horrifyingly, improperly,
   inexcusably, infamously, infernally, inordinately, intolerably,
   lamentably, loathsomely, miserably, nakedly, nastily, nauseatingly,
   notoriously, obnoxiously, odiously, offensively, openly,
   outrageously, painfully, piteously, repugnantly, repulsively,
   revoltingly, sadly, savagely, scandalously, shabbily, shamefully,
   shatteringly, shockingly, something awful, something fierce,
   sordidly, sorely, staggeringly, startlingly, strikingly,
   surpassingly, terribly, terrifically, torturously, tragically,
   tremendously, unashamedly, unbearably, unconscionably, unduly,
   unpardonably, viciously, vilely, woefully, wretchedly

Dreadfully >> D Words
Dreadfully, definition of term: Dreadfully
dreadfully_pag1.html