Where does “*borstile” come from?

*borstile (Middle English) comes from Old English stiġel, from Proto-West Germanic *stigilu.

Ancestry of “*borstile”, step by step

Step	Language	Word	Meaning
1	Old English	stiġel	stile, set of steps for getting over a fence
2	Proto-West Germanic	*stigilu	—

*borstile — Etymology, Origin & Word History | Etymology Explorer