Source : Webster's Revised Unabridged Dictionary (1913)

Disingenuous \Dis`in*gen"u*ous\, a.
   1. Not noble; unbecoming true honor or dignity; mean;
      unworthy; as, disingenuous conduct or schemes.

   2. Not ingenuous; wanting in noble candor or frankness; not
      frank or open; uncandid; unworthily or meanly artful.

            So disingenuous as not to confess them [faults].
                                                  --Pope.
      -- {Dis`in*gen"u*ous*ly}, adv. --T. Warton. --
      {Dis`in*gen"u*ous*ness}, n. --Macaulay.

Source : WordNet®

disingenuousness
     n : the quality of being disingenuous and lacking candor [ant: {ingenuousness}]