Source : Webster's Revised Unabridged Dictionary (1913)

Frolicsome \Frol"ic*some\, a.
   Full of gayety and mirth; given to pranks; sportive.

         Old England, who takes a frolicsome brain fever once
         every two or three years, for the benefit of her
         doctors.                                 --Sir W.
                                                  Scott.
   -- {Frol"ic*some*ly}, adv. -- {Frol"ic*some*ness}, n.

Source : WordNet®

frolicsomeness
     n : lively high-spirited playfulness [syn: {friskiness}, {sportiveness}]