The Collaborative International Dictionary of English v.0.48:

genuine \gen"u*ine\, a. [L. genuinus, fr. genere, gignere, to
   beget, in pass., to be born: cf. F. g['e]nuine. See
   Gender.]
   Belonging to, or proceeding from, the original stock; native;
   hence, not counterfeit, spurious, false, or adulterated;
   authentic; real; natural; true; pure; as, a genuine text; a
   genuine production; genuine materials. "True, genuine night."
   --Dryden.

   Syn: Authentic; real; true; pure; unalloyed; unadulterated.
        See Authentic. -- Gen"u*ine*ly, adv. --
        Gen"u*ine*ness, n.
        [1913 Webster]

              The evidence, both internal and external, against
              the genuineness of these letters, is overwhelming.
                                                  --Macaulay.
        [1913 Webster]

WordNet (r) 3.0 (2006):

genuinely
    adv 1: in accordance with truth or fact or reality; "she was now
           truly American"; "a genuinely open society"; "they don't
           really listen to us" [syn: truly, genuinely,
           really]
    2: genuinely; with authority; "it is authentically British"
       [syn: authentically, genuinely]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "genuinely":
   absolutely, actually, all joking aside, artlessly, authentically,
   bluffly, bluntly, broadly, brusquely, candidly, de facto, directly,
   frankly, guilelessly, honestly, in actuality, in all conscience,
   in all seriousness, in effect, in fact, in plain English,
   in plain words, in reality, ingenuously, legitimately, manifestly,
   naturally, obviously, openheartedly, openly, outspokenly,
   plain-spokenly, plainly, positively, really, roundly, simply,
   sincerely, straightforwardly, truly, unaffectedly, unassumedly,
   unconstrainedly, unreservedly, unrestrainedly, veridically,
   veritably, warts and all, with no nonsense