Where does “drw(y)st'” come from?

drw(y)st' (Middle Persian) comes from Proto-Indo-Iranian dʰruwás, from Proto-Indo-European dʰru-wó-s, from Proto-Indo-European -wós — Creates adjectives from verb stems.

Ancestry of “drw(y)st'”, step by step

StepLanguageWordMeaning
1Proto-Indo-Iraniandʰruwásfixed, firm
2Proto-Indo-Europeandʰru-wó-s—
3Proto-Indo-European-wósCreates adjectives from verb stems
Every word from Proto-Indo-European -wós →Every word from Proto-Indo-European dʰru-wó-s →Every word from Proto-Indo-Iranian dʰruwás →