Where does “nichtóry” come from?

nichtóry (Polish) comes from Polish który, from Proto-Slavic kotorъ, from Proto-Indo-European kʷóteros, from Proto-Indo-European kʷos, from Proto-Indo-European kʷ- — The primary interrogative root.

Ancestry of “nichtóry”, step by step

StepLanguageWordMeaning
1Polishktórywhat, which one; that, who, which
2Proto-Slavickotorъwhich
3Proto-Indo-Europeankʷóteroswhich of two
4Proto-Indo-EuropeankʷosSee *kʷis
5Proto-Indo-Europeankʷ-The primary interrogative root
Every word from Proto-Indo-European kʷ- →Every word from Proto-Indo-European kʷos →Every word from Proto-Indo-European kʷóteros →