Where does “авосе” come from?

авосе (Old East Slavic) comes from Old East Slavic а, from Proto-Slavic a, from Proto-Balto-Slavic ō, from Proto-Indo-European h₁ōd.

Ancestry of “авосе”, step by step

авосе traces back through two separate lines of ancestry.

via Old East Slavic а

StepLanguageWordMeaning
1Old East Slavicаbut, and
2Proto-Slavicabut; and
3Proto-Balto-Slavicōand; but
4Proto-Indo-Europeanh₁ōd—

via Old East Slavic осе

StepLanguageWordMeaning
1Old East Slavicосеhere
Every word from Proto-Indo-European h₁ōd →Every word from Proto-Balto-Slavic ō →Every word from Proto-Slavic a →