Where does “Ob” come from?

Ob (Polish) comes from Russian Обь, from Proto-Indo-Iranian Hap-, from Proto-Indo-European h₁ep- — to take.

Ancestry of “Ob”, step by step

StepLanguageWordMeaning
1RussianОбьOb (Russian icebreaker)
2Proto-Indo-IranianHap-—
3Proto-Indo-Europeanh₁ep-to take
Every word from Proto-Indo-European h₁ep- →Every word from Proto-Indo-Iranian Hap- →Every word from Russian Обь →