Where does “попутник” come from?

попутник (Ukrainian) comes from Ukrainian По, from Italian Po, from Latin Padus, from Lepontic Bodincus, from Proto-Indo-European bʰudʰmḗn, from Proto-Indo-European dʰewbʰ-, from Proto-Indo-European dʰewh₂- — smoke; mist, haze.

попутник (Ukrainian): fellow traveller, travelling companion one who travels together with another

Definitions

fellow traveller, travelling companion one who travels together with another

Ancestry of “попутник”, step by step

попутник traces back through two separate lines of ancestry.

via Ukrainian По

Step	Language	Word	Meaning
1	Ukrainian	По	Petro Poroshenko
2	Italian	Po	—
3	Latin	Padus	the River Po
4	Lepontic	Bodincus	—
5	Proto-Indo-European	bʰudʰmḗn	bottom
6	Proto-Indo-European	dʰewbʰ-	deep
7	Proto-Indo-European	dʰewh₂-	smoke; mist, haze

via Russian путь

Step	Language	Word	Meaning
1	Russian	путь	way, path, road; track, line; means
2	Proto-Slavic	pǫtь	way, path
3	Proto-Balto-Slavic	pántis	way, path, road
4	Proto-Indo-European	póntoh₁s	path
5	Proto-Indo-European	pent-	to pass; path

Every word from Proto-Indo-European dʰewh₂- →Every word from Proto-Indo-European dʰewbʰ- →Every word from Proto-Indo-European bʰudʰmḗn →