noun
merrymaking; partying
Refers to enjoying oneself at a lively gathering, often with food and drink. Somewhat literary or formal in tone.
宴楽の夜は更けていった。
The night of merrymaking grew late.
彼らは宴楽にふけっていた。
They were indulging in partying.
Compound of 宴 (feast, banquet) and 楽 (pleasure, enjoyment). The exact historical derivation is uncertain, but the combination naturally conveys the idea of enjoying a feast.