Where does “Cameroun” come from?

Cameroun (French) comes from Portuguese Camarões, from Portuguese Rio dos Camarões — River of Shrimps.

Ancestry of “Cameroun”, step by step

Step	Language	Word	Meaning
1	Portuguese	Camarões	—
2	Portuguese	Rio dos Camarões	River of Shrimps

Cameroun — Etymology, Origin & Word History | Etymology Explorer