Feast
Middle English: from Old French feste (noun), fester (verb), from Latin festa, neuter plural of festus ‘joyous’. Compare with fete and fiesta.
wiktionary
From Middle English feeste, feste, borrowed from Old French feste, from Late Latin festa, from the plural of Latin festum(“holiday, festival, feast”), ultimately from Proto-Indo-European *dʰéh₁s(“god, godhead, deity”); see also Ancient Greek θεός(theós, “god, goddess”). More at theo-. Doublet of fete and fiesta.
From Middle English feesten, festen, from Old French fester, from Medieval Latin festāre, from the noun. See above.
etymonline
feast (n.)
c. 1200, "secular celebration with feasting and entertainment" (often held on a church holiday); c. 1300, "religious anniversary characterized by rejoicing" (rather than fasting), from Old French feste "religious festival, holy day; holiday; market, fair; noise, racket; jest, fun" (12c., Modern French fête), from Vulgar Latin *festa (fem. singular; also source of Italian festa, Spanish fiesta), from Latin festa "holidays, feasts, festal banquets," noun use of neuter plural of festus "festive, joyful, merry," related to feriae "holiday" and fanum "temple," from Proto-Italic *fasno- "temple," from PIE *dhis-no- "divine, holy; consecrated place," suffixed form of PIE root *dhes-, forming words for religious concepts.
The spelling -ea- was used in Middle English to represent the sound we mis-call "long e." Meaning "abundant meal" (whether public or private) is by late 14c. Meaning "any enjoyable occasion or event" is from late 14c.
feast (v.)
c. 1300, "partake of a feast," from Old French fester "to feast, make merry; observe (a holiday)" (Modern French fêter), from feste "religious festival" (see feast (n.)). Related: Feasted; feasting.
