Where does “hamr” come from?

hamr (Old Norse) comes from Proto-Germanic hamô, from Proto-Indo-European ḱem- — to cover, conceal; hornless.

hamr (Old Norse): skin, slough hleypa hǫmum ― to cast the slough;...

Definitions

Step	Language	Word	Meaning
1	Proto-Germanic	hamô	cover, skin; clothes, skirt, fishnet; harness,...
2	Proto-Indo-European	ḱem-	to cover, conceal; hornless

hamr — Etymology, Origin & Word History | Etymology Explorer