Where does “четвёртый” come from?
четвёртый (Russian) comes from Old East Slavic четвьртъ, from Proto-Slavic četvьrtъ, from Proto-Balto-Slavic ketwirtas, from Proto-Indo-European *kʷetwr̥tós.
четвёртый (Russian): fourth
Ancestry of “четвёртый”, step by step
Words derived from “четвёртый”