Where does “Dniester” come from?

Dniester (English) comes from Russian Днестр, from Old East Slavic Дънѣстръ, from Proto-Slavic *Dъněstrъ.

Ancestry of “Dniester”, step by step

Step	Language	Word	Meaning
1	Russian	Днестр	Dniester
2	Old East Slavic	Дънѣстръ	—
3	Proto-Slavic	*Dъněstrъ	—

Dniester — Etymology, Origin & Word History | Etymology Explorer