Where does “reunaoja” come from?

reunaoja (Finnish) comes from Finnish oja, from Proto-Slavic oje, from Proto-Indo-European h₂oyHsos.

Ancestry of “reunaoja”, step by step

reunaoja traces back through two separate lines of ancestry.

via Finnish oja

StepLanguageWordMeaning
1Finnishojaditch, trench; small natural brook
2Proto-Slavicojethill, shaft
3Proto-Indo-Europeanh₂oyHsos—

via Finnish reuna

StepLanguageWordMeaning
1Finnishreunarim; brink, edge, border; boundary
2Proto-Finnicreunaedge
Every word from Proto-Indo-European h₂oyHsos →Every word from Proto-Slavic oje →Every word from Finnish oja →