Where does “Transnigerian” come from?

Transnigerian (English) comes from English trans-, from Latin trāns, from Latin Padus, from Lepontic Bodincus, from Proto-Indo-European bʰudʰmḗn, from Proto-Indo-European dʰewbʰ-, from Proto-Indo-European dʰewh₂- — smoke; mist, haze.

Transnigerian (English): Crossing or spanning the Niger (river or valley)

Definitions

Crossing or spanning the Niger (river or valley)

Ancestry of “Transnigerian”, step by step

Step	Language	Word	Meaning
1	English	trans-	Across, through, over, beyond, to or on the other...
2	Latin	trāns	across, beyond
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

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