Where does “nionde” come from?

nionde (Swedish) comes from Old Swedish niundi, from Old Norse níundi, from Proto-Germanic newundô — ninth.

nionde (Swedish): ninth

Definitions

Step	Language	Word	Meaning
1	Old Swedish	niundi	ninth
2	Old Norse	níundi	ninth
3	Proto-Germanic	newundô	ninth

nionde — Etymology, Origin & Word History | Etymology Explorer