Where does “åttonde” come from?

åttonde (Swedish) comes from Norwegian Nynorsk åttande, from Old Norse áttandi, from Proto-Germanic ahtudô — eighth.

åttonde (Swedish): eighth

Definitions

Step	Language	Word	Meaning
1	Norwegian Nynorsk	åttande	eighth
2	Old Norse	áttandi	—
3	Proto-Germanic	ahtudô	eighth

åttonde — Etymology, Origin & Word History | Etymology Explorer