Where does “compilour” come from?

compilour (Old French) comes from Old French compileur, from Latin compilatorem — accusative singular of compīlātor.

Ancestry of “compilour”, step by step

Step	Language	Word	Meaning
1	Old French	compileur	—
2	Latin	compilatorem	accusative singular of compīlātor

compilour — Etymology, Origin & Word History | Etymology Explorer