The Collaborative International Dictionary of English v.0.48:

Grossly \Gross"ly\, adv.
   In a gross manner; greatly; coarsely; without delicacy;
   shamefully; disgracefully.
   [1913 Webster]

WordNet (r) 3.0 (2006):

grossly
    adv 1: in a gross manner

Moby Thesaurus II by Grady Ward, 1.0:

77 Moby Thesaurus words for "grossly":
   abjectly, abominably, arrantly, atrociously, awfully, basely,
   bestially, brutally, coarsely, contemptibly, crassly, crudely,
   despicably, detestably, disgustingly, dreadful, dreadfully,
   egregiously, excessively, execrably, exorbitantly, extortionately,
   extravagantly, flagrantly, foully, fulsomely, gougingly, heinously,
   horribly, horridly, immoderately, improperly, indecently,
   indecorously, indelicately, inelegantly, infamously, inordinately,
   loathsomely, meanly, miserably, monstrously, nastily, nauseatingly,
   nefariously, notoriously, obnoxiously, odiously, offensively,
   outrageously, pettily, poorly, preposterously, ribaldly, roughly,
   rudely, savagely, scandalously, scurvily, shabbily, shamefully,
   shockingly, shoddily, something fierce, sordidly, terribly,
   unconscionably, uncouthly, unduly, unreasonably, unseemly,
   untastefully, usuriously, viciously, vilely, vulgarly,
   wretchedly