Where does “czyść” come from?
czyść (Old Polish) comes from Proto-Slavic *čistì, from Proto-Balto-Slavic (s)keistéi, from Proto-Indo-European *(s)kʷéyt-t ~ *(s)kit-ént, from Proto-Indo-European kʷeyt- — to notice; to read.
czyść (Old Polish): to read
Ancestry of “czyść”, step by step