From Old Frenchfestival, from Late LatinfÄ“stÄ«vÄlis, from LatinfÄ“stÄ«vus ("festive").
Full definition of festival
Adjective
festival
Pertaining to a feast or feast-day. (Now only as the noun used attributively.)
1590, Edmund Spenser, The Faerie Queene, II.iii:the temple of the Gods ... Whom all the people decke with girlands greene, And honour in their festiuall resort ....