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):

genuineness
    n 1: the state of being genuine [ant: spuriousness]
    2: undisputed credibility [syn: authenticity, genuineness,
       legitimacy]