Where does “brine” come from?

brine (Middle English) comes from Old English brīne, from Proto-Germanic brīnijaz, from Proto-Indo-European bʰreyH- — to cut.

Ancestry of “brine”, step by step

Step	Language	Word	Meaning
1	Old English	brīne	—
2	Proto-Germanic	brīnijaz	—
3	Proto-Indo-European	bʰreyH-	to cut

brine — Etymology, Origin & Word History | Etymology Explorer