Where does “buok” come from?

buok (Elfdalian) comes from Old Norse bók, from Proto-Germanic bōks, from Proto-Indo-European bʰeh₂ǵos — beech.

buok (Elfdalian): book

Definitions

Step	Language	Word	Meaning
1	Old Norse	bók	beech; textile fabric with figures woven in it;...
2	Proto-Germanic	bōks	letter, written message, inscriptions carved into...
3	Proto-Indo-European	bʰeh₂ǵos	beech

buok — Etymology, Origin & Word History | Etymology Explorer