Where does “быстрыи” come from?

быстрыи (Old East Slavic) comes from Proto-Slavic bystrъ, from Proto-Indo-European bʰūsro-.

Ancestry of “быстрыи”, step by step

StepLanguageWordMeaning
1Proto-Slavicbystrъquick; penetrating, transparent
2Proto-Indo-Europeanbʰūsro-—

Words derived from “быстрыи”

Every word from Proto-Indo-European bʰūsro- →Every word from Proto-Slavic bystrъ →