Where does “фестивальный” come from?
фестивальный (Russian) comes from Russian фестива́ль, from English festival, from Old French festival, from Latin fēstīvālis, from Latin fēstīvus, from Latin -īvus, from Proto-Indo-European -iHwós, from Proto-Indo-European -wós — Creates adjectives from verb stems.
фестивальный (Russian): festival
Ancestry of “фестивальный”, step by step