inexcusably

from WordNet (r) 3.0 (2006)

inexcusably
    adv 1: in an unpardonable manner or to an unpardonable degree;
           "he was inexcusably cruel to his wife" [syn:
           {inexcusably}, {unpardonably}, {unforgivably}] [ant:
           {excusably}, {forgivably}, {pardonably}]
    2: without any excuse; "he is unjustifiably harsh on her" [syn:
       {unjustifiably}, {inexcusably}] [ant: {justifiably}]

from The Collaborative International Dictionary of English v.0.48

Inexcusably \In`ex*cus"a*bly\, adv.
   With a degree of guilt or folly beyond excuse or
   justification.
   [1913 Webster]

         Inexcusably obstinate and perverse.      --Jortin.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

72 Moby Thesaurus words for "inexcusably":
      abominably, agonizingly, awfully, baldly, balefully, bitterly,
      blatantly, brashly, confoundedly, cruelly, damnably, deadly,
      deathly, deucedly, distressingly, dolorously, dreadfully,
      egregiously, excessively, excruciatingly, exorbitantly,
      extravagantly, flagrantly, frightfully, grievously, hellishly,
      horribly, improperly, indefensibly, inexpiably, infernally,
      iniquitously, inordinately, interestedly, intolerably,
      irremissibly, lamentably, miserably, nakedly, one-sidedly, openly,
      painfully, partially, piteously, sadly, shatteringly, shockingly,
      something awful, something fierce, sorely, staggeringly, terribly,
      torturously, unallowably, unashamedly, unbearably, unconscionably,
      undeservedly, undispassionately, unduly, unequally, unevenly,
      unfairly, unforgivably, unjustifiably, unjustly, unpardonably,
      unreasonably, unwarrantably, woefully, wrongfully, wrongly