Where does “festal” come from?

festal (Middle French) comes from Latin festum, from Latin fēstus, from Proto-Italic fēstos.

Ancestry of “festal”, step by step

Step	Language	Word	Meaning
1	Latin	festum	a holiday, festival; a banquet, feast
2	Latin	fēstus	—
3	Proto-Italic	fēstos	—