Where does “пором” come from?

пором (Russian) comes from Proto-Slavic pormъ, from Proto-Indo-European pórmos, from Proto-Indo-European per-, from Proto-Indo-European pr̥tós — passed , crossed.

Ancestry of “пором”, step by step

StepLanguageWordMeaning
1Proto-Slavicpormъferry
2Proto-Indo-Europeanpórmos—
3Proto-Indo-Europeanper-before, in front; first; to go through
4Proto-Indo-Europeanpr̥tóspassed , crossed
Every word from Proto-Indo-European pr̥tós →Every word from Proto-Indo-European per- →Every word from Proto-Indo-European pórmos →