Meaning

noun a day or period of time set aside for feasting and celebration

noun an organized series of acts and performances (usually in one place)

originFrom Middle English festival (adjective), from Old French festival (“festive”), from Late Latin fēstīvālis, from Latin fēstīvus (“festive”). By surface analysis, festive + -al. Displaced native Old English frēols. The noun is shortened from festival day, from Middle English festival dai, festiuall day (“feast day, festival”).

Etymology from Wiktionary, CC BY-SA 3.0