The Collaborative International Dictionary of English v.0.48:

Blithesome \Blithe"some\ (-s[u^]m), a.
   Cheery; gay; merry.
   [1913 Webster]

         The blithesome sounds of wassail gay.    --Sir W.
                                                  Scott.
   [1913 Webster] -- Blithe"some*ly, adv. --
   Blithe"some*ness, n.
   [1913 Webster]