Where does “ātra-” come from?

ātra- (Proto-Balto-Slavic) comes from Proto-Indo-European ētro- — quick, fast.

Ancestry of “ātra-”, step by step

StepLanguageWordMeaning
1Proto-Indo-Europeanētro-quick, fast
Every word from Proto-Indo-European ētro-
ātra- — Etymology, Origin & Word History | Etymology Explorer