Where does “штодзень” come from?

штодзень (Belarusian) comes from Belarusian што, from Proto-Slavic čьto, from Proto-Balto-Slavic ki, from Proto-Indo-European kʷíd, from Proto-Indo-European kʷís, from Proto-Indo-European kʷi- — interrogative base.

Ancestry of “штодзень”, step by step

штодзень traces back through two separate lines of ancestry.

via Belarusian што

StepLanguageWordMeaning
1Belarusianштоthat; that, which; what
2Proto-Slavicčьtowhat
3Proto-Balto-Slavickiwhat
4Proto-Indo-Europeankʷídneuter nominative/accusative singular of *kʷís
5Proto-Indo-Europeankʷíswho, what; who, which, that; which, what
6Proto-Indo-Europeankʷi-interrogative base

via Belarusian дзень

StepLanguageWordMeaning
1Belarusianдзеньday
2Slovakdeňday
3Proto-Slavicdь̑nьday
Every word from Proto-Indo-European kʷi-Every word from Proto-Indo-European kʷísEvery word from Proto-Indo-European kʷíd