Where does “tretti” come from?

tretti (Norwegian Nynorsk) comes from Old Norse þrír tigir, from Proto-Germanic þrīz tigiwiz — thirty.

tretti (Norwegian Nynorsk): thirty

Definitions

Step	Language	Word	Meaning
1	Old Norse	þrír tigir	thirty
2	Proto-Germanic	þrīz tigiwiz	thirty

tretti — Etymology, Origin & Word History | Etymology Explorer