Where does “finial” come from?

finial (Middle English) comes from Old French final, from Latin fīnālis, from Latin -ālis, from Proto-Italic -ālis.

Ancestry of “finial”, step by step

Step	Language	Word	Meaning
1	Old French	final	final, definitive, last
2	Latin	fīnālis	—
3	Latin	-ālis	—
4	Proto-Italic	-ālis	—

finial — Etymology, Origin & Word History | Etymology Explorer