It may sound like a cliche, but Christmastime has for many centuries been considered to be a happy, joyful time of the year: not only where we find joy ourselves, but when we wish goodwill to all men. And what's not to be joyful about? Families getting together, parties with friends, gift-giving, over-indulging on scrumptious food, and an excuse not to get up and go out to work!
Since the time of the Romans' festival of Saturnalia, and the Celt's Yule, the time of the Winter Solstice has been associated with merrymaking, singing and feasting.
For the epitome of a joyful name, you can't do better than Joy itself, which is derived from the Old French Joie, and ultimately the Latin Gaudia. The similar-sounding, but exotically spelt Gioia is the Italian form. Bliss is another option taken from the English language, as is Blithe / Blythe. And, on occasion, Happy and Merry have seen some usage as first names.
The Ancient Greeks had the word όλβιος (olbios) "happy, fortunate", found in the names Olbios, Olbia, Olbiades and Nikolbios; and xαρά (chara) "joy, delight" in Chara, Chareis and Chairon.
As well as Gaudia, Latin also gives us felix "happy" from which we get names such as Felix, Felicity, Felicitas, Felice, Felicia and Felicidad. There is also laetus "joyful," found in the Roman names Laetus and Laeta; and Laetitia "joy, delight," which became Lettice in the Middle Ages.
The decendant language of Italian gives us Allegra, Fortunato and Gioconda.
The Hebrew word for "joy" is גיל (gil) and is found in the names Gil, Gila, Gilat, Gilad and Gili. There is also אושר (osher) "happiness" used in the forms Asher and Osher.
The Yiddish name meaning joy is Freyde, while Selig, Zelig and Zelda come from the Yiddish word for "happy."
Bahij, Bahija or Bahija are Arabic names from بهيجة (bahija) "joyful". Farah or Farrah mean "joy," while Fariha, Hani and Said mean "happy" and Hana means "bliss, happiness."
Anand, Nanda, Nandita, Pramoda, Priti, Sharma and Sharmila are all Sanskrit names with "joyful" meanings.
Some of my personal favourite "joy" names include Alaia (Basque), Kalea (Hawaiian) and Lowenna (Cornish).