The Collaborative International Dictionary of English v.0.48:

Joyous \Joy"ous\, a. [OE. joyous, joious, joios, F. joyeux.See
   Joy.]
   Glad; gay; merry; joyful; also, affording or inspiring joy;
   with of before the word or words expressing the cause of joy.
   [1913 Webster]

         Is this your joyous city?                --Is. xxiii.
                                                  7.
   [1913 Webster]

         They all as glad as birds of joyous prime. --Spenser.
   [1913 Webster]

         And joyous of our conquest early won.    --Dryden.

   Syn: Merry; lively; blithe; gleeful; gay; glad; mirthful;
        sportive; festive; joyful; happy; blissful; charming;
        delightful. -- Joy"ous*ly, adv. -- Joy"ous*ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

joyous
    adj 1: full of or characterized by joy; "felt a joyous abandon";
           "joyous laughter" [ant: joyless]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "joyous":
   animating, beaming, beatific, beatified, blessed, blissful, buxom,
   capering, cheerful, cheering, cheery, chirping, convivial, dancing,
   ecstatic, encouraging, enlivening, exhilarating, festal, festive,
   flushed with joy, frivolous, gala, gay, glad, gladdening, gladsome,
   gleeful, glowing, happy, heart-warming, heartening, hilarious,
   inspiring, inspiriting, invigorating, jocular, jocund, jolly,
   jovial, joyful, laughing, laughter-loving, leaping, lighthearted,
   merry, merrymaking, mirth-loving, mirthful, on the loose, purring,
   radiant, rapturous, rejoicing, risible, singing, smiling, smirking,
   sparkling, starry-eyed, thrice happy, transported