Where does “bratówka” come from?

bratówka (Polish) comes from Polish bratowa, from Polish brat, from Old Polish brat, from Proto-Slavic bratrъ, from Proto-Balto-Slavic brā́ˀtē, from Proto-Indo-European bʰréh₂tēr — brother.

Ancestry of “bratówka”, step by step

StepLanguageWordMeaning
1Polishbratowasister-in-law
2Polishbratbrother
3Old Polishbratbrother
4Proto-Slavicbratrъbrother
5Proto-Balto-Slavicbrā́ˀtēbrother
6Proto-Indo-Europeanbʰréh₂tērbrother
Every word from Proto-Indo-European bʰréh₂tēr →Every word from Proto-Balto-Slavic brā́ˀtē →Every word from Proto-Slavic bratrъ →