Search Result for "lightheartedness": 
Wordnet 3.0

NOUN (1)

1. the cheerful feeling you have when nothing is troubling you;
[syn: carefreeness, insouciance, lightheartedness, lightsomeness]



The Collaborative International Dictionary of English v.0.48:

Light-hearted \Light"-heart`ed\ (l[imac]t"h[aum]rt`[e^]d), a.
   Free from grief or anxiety; gay; cheerful; merry. --
   Light"-heart`ed*ly, adv. -- Light"-heart`ed*ness, n.
   [1913 Webster]


WordNet (r) 3.0 (2006):

lightheartedness
    n 1: the cheerful feeling you have when nothing is troubling you
         [syn: carefreeness, insouciance, lightheartedness,
         lightsomeness]