Where does “бор” come from?

бор (Serbo-Croatian) comes from New Latin borum, from Arabic بَوْرَق, from Persian بوره, from Middle Persian bwlk'.

Ancestry of “бор”, step by step

Step	Language	Word	Meaning
1	New Latin	borum	—
2	Arabic	بَوْرَق	—
3	Persian	بوره	borax; sugar
4	Middle Persian	bwlk'	—

бор — Etymology, Origin & Word History | Etymology Explorer