Source : Webster's Revised Unabridged Dictionary (1913)

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

Source : WordNet®

light-heartedly
     adv : in a light-hearted manner; "he light-heartedly overlooks
           some of the basic facts of life" [syn: {lightsomely}]