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

bitterly \bit"terly\, adv.
   in a bitter manner.
   1913 webster

[2] : WordNet (r) 2.0

bitterly
     adv 1: in a resentful manner; "she complained bitterly" syn: with
            bitterness
     2: indicating something hard to accept; "he was bitterly
        disappointed"
     3: extremely and sharply; "it was bitterly cold"; "bitter cold"
        syn: piercingly, bitingly, bitter
see also:
with bitterness piercingly bitingly bitter 

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

77 moby thesaurus words for "bitterly":
   abominably, acerbically, acerbly, acidly, acridly, acrimoniously,
   agonizingly, awfully, baldly, balefully, bitingly, blatantly,
   brashly, caustically, confoundedly, corrodingly, corrosively,
   cruelly, cuttingly, damnably, deadly, deathly, deucedly,
   distressingly, dolorously, dreadfully, egregiously, excessively,
   excruciatingly, exorbitantly, extravagantly, flagrantly,
   frightfully, grievously, hardly, hellishly, horribly, improperly,
   incisively, inexcusably, infernally, inordinately, intolerably,
   keenly, lamentably, miserably, mordaciously, mordantly, nakedly,
   openly, painfully, penetratingly, piercingly, piteously,
   rancorously, sadly, scathingly, scorchingly, sharply, shatteringly,
   shockingly, something awful, something fierce, sorely, stabbingly,
   staggeringly, tartly, terribly, torturously, trenchantly,
   unashamedly, unbearably, unconscionably, unduly, unpardonably,
   witheringly, woefully

Bitterly >> B Words
Bitterly, definition of term: Bitterly
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