Where does “четвьртъкъ” come from?

четвьртъкъ (Old East Slavic) comes from Proto-Slavic četvьrtъkъ, from Proto-Slavic četvьrtъ, from Proto-Balto-Slavic ketwirtas, from Proto-Indo-European *kʷetwr̥tós — fourth.

Ancestry of “четвьртъкъ”, step by step

StepLanguageWordMeaning
1Proto-SlavicčetvьrtъkъThursday
2Proto-Slavicčetvьrtъfourth
3Proto-Balto-Slavicketwirtasfourth
4Proto-Indo-European*kʷetwr̥tósfourth

Words derived from “четвьртъкъ”

Every word from Proto-Indo-European *kʷetwr̥tós →Every word from Proto-Balto-Slavic ketwirtas →Every word from Proto-Slavic četvьrtъ →