Source : Webster's Revised Unabridged Dictionary (1913)

Lightsome \Light"some\ (l[imac]t"s[u^]m), a.
   1. Having light; lighted; not dark or gloomy; bright.

            White walls make rooms more lightsome than black.
                                                  --Bacon.

   2. Gay; airy; cheering; exhilarating.

            That lightsome affection of joy.      --Hooker.
      -- {Light"some*ly}, adv. -- {Light"some*ness}, n.

            Happiness may walk soberly in dark attire, as well
            as dance lightsomely in a gala dress. --Hawthorne.

Source : WordNet®

lightsomely
     adv 1: moving with quick light steps; "she walked lightsomely down
            the long staircase" [syn: {trippingly}]
     2: in a light-hearted manner; "he light-heartedly overlooks
        some of the basic facts of life" [syn: {light-heartedly}]