The Collaborative International Dictionary of English v.0.48:

Harshly \Harsh"ly\, adv.
   In a harsh manner; gratingly; roughly; rudely.
   [1913 Webster]

         'T will sound harshly in her ears.       --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

harshly
    adv 1: in a harsh or unkind manner; "`That's enough!,' he cut in
           harshly"
    2: in a harsh and grating manner; "her voice fell gratingly on
       our ears" [syn: gratingly, raspingly, harshly]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "harshly":
   abruptly, austerely, badly, bearishly, bluffly, bluntly, boorishly,
   brashly, brusquely, cavalierly, churlishly, cruelly, crustily,
   curtly, grimly, gruffly, hardly, heartlessly, inclemently,
   inexorably, mercilessly, nastily, painfully, pitilessly,
   relentlessly, remorselessly, rigorously, roughly, ruggedly,
   ruthlessly, severely, sharply, shortly, snippily, sternly,
   strictly, stringently, toughly, uncompassionately, unforgivingly,
   unmercifully, unremorsefully, unsparingly, unsympathetically,
   unyieldingly