ancient quadrennial festival of the Ionians, held on Delos (hence the name) in honour of the Greek god Apollo. The local title was Apollonia, which seems always to have been used for the corresponding yearly festival. It later declined along with the political importance of Ionia but was revived in 426 BC by the Athenians as part of their imperial policy.
DELIA
Meaning of DELIA in English
Britannica English vocabulary. Английский словарь Британика. 2012