The Collaborative International Dictionary of English v.0.48:

Immaculate \Im*mac"u*late\, a. [L. immaculatus; pref. im- not +
   maculatus, p. p. of maculare to spot, stane, fr. macula spot.
   See Mail armor.]
   Without stain or blemish; spotless; undefiled; clear; pure.
   [1913 Webster]

         Were but my soul as pure
         From other guilt as that, Heaven did not hold
         One more immaculate.                     --Denham.
   [1913 Webster]

         Thou sheer, immaculate and silver fountain. --Shak.
   [1913 Webster]

   Immaculate conception (R. C. Ch.), the doctrine that the
      Virgin Mary was conceived without original sin. --
      Im*mac"u*late*ly, adv. -- Im*mac"u*late*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

immaculately
    adv 1: in an immaculate manner; "gone was the casually dressed
           Canadian she had thought a backwoodsman--this man was
           immaculately tailored"

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "immaculately":
   absolutely, blamelessly, clean, cleanly, completely,
   conscientiously, decently, entirely, erectly, fastidiously,
   faultlessly, flawlessly, fully, high-mindedly, honestly, honorably,
   ideally, impeccably, infallibly, irreproachably, just right,
   meticulously, morally, nobly, perfectly, punctiliously, purely,
   reputably, righteously, scrupulously, spotlessly, stainlessly,
   thoroughly, totally, unimpeachably, unspottedly, uprightly,
   upstandingly, virtuously, wholly, worthily