Source : Webster's Revised Unabridged Dictionary (1913)

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.

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

Source : WordNet®

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