Source : Webster's Revised Unabridged Dictionary (1913)

Mirthful \Mirth"ful\, a.
   1. Full of mirth or merriment; merry; as, mirthful children.

   2. Indicating or inspiring mirth; as, a mirthful face.

            Mirthful, comic shows.                --Shak.
      -- {Mirth"ful*ly}, adv. -- {Mirth"ful*ness}, n.

Source : WordNet®

mirthfully
     adv : in a joyous manner; "they shouted happily" [syn: {happily},
           {merrily}, {gayly}, {blithely}, {jubilantly}, {with
           happiness}] [ant: {unhappily}]