Source : Webster's Revised Unabridged Dictionary (1913)

Wittiness \Wit"ti*ness\, n.
   The quality of being witty.

Source : WordNet®

wittiness
     n : a message whose ingenuity or verbal skill or incongruity has
         the power to evoke laughter [syn: {wit}, {humor}, {humour},
          {witticism}]