Source : Webster's Revised Unabridged Dictionary (1913)

Humorousness \Hu"mor*ous*ness\, n.
   1. Moodiness; capriciousness.

   2. Facetiousness; jocularity.

Source : WordNet®

humorousness
     n : the trait of merry joking [syn: {jocoseness}, {jocosity}, {merriness}]