Where does “katter” come from?

katter (Old Swedish) comes from Old Norse kǫttr, from Proto-Germanic kattuz, from Latin cattus, from Latin catta — a cat.

Ancestry of “katter”, step by step

Step	Language	Word	Meaning
1	Old Norse	kǫttr	cat
2	Proto-Germanic	kattuz	cat
3	Latin	cattus	a cat
4	Latin	catta	a cat

katter — Etymology, Origin & Word History | Etymology Explorer