The Collaborative International Dictionary of English v.0.48:

Gleeful \Glee"ful\, a.
   Merry; gay; joyous. --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gleeful
    adj 1: full of high-spirited delight; "a joyful heart" [syn:
           elated, gleeful, joyful, jubilant]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "gleeful":
   blithe, blithesome, boon, buxom, cheerful, delighted, ecstatic,
   elated, exhilarated, exuberant, exultant, frivolous, gay, happy,
   hilarious, jocular, jocund, jolly, jovial, joyful, joyous,
   jubilant, laughter-loving, lighthearted, merry, mirth-loving,
   mirthful, overjoyed, pleased, rapturous, rejoicing, risible