Where does “mywać” come from?

mywać (Polish) comes from Polish myć, from Proto-Slavic myti, from Proto-Indo-European muH-.

Ancestry of “mywać”, step by step

StepLanguageWordMeaning
1Polishmyćto wash, to clean with water; to wash oneself
2Proto-Slavicmytito wash
3Proto-Indo-EuropeanmuH-—
Every word from Proto-Indo-European muH- →Every word from Proto-Slavic myti →Every word from Polish myć →
mywać — Etymology, Origin & Word History | Etymology Explorer