Where does “Bósforo” come from?

Bósforo (Portuguese) comes from Medieval Latin Bosphorus, from Ancient Greek Βόσπορος, from Ancient Greek πόρος, from Ancient Greek πείρω, from Proto-Hellenic *péryō.

Ancestry of “Bósforo”, step by step

Step	Language	Word	Meaning
1	Medieval Latin	Bosphorus	—
2	Ancient Greek	Βόσπορος	Bosporus
3	Ancient Greek	πόρος	a means of passage, passageway, way, opening;...
4	Ancient Greek	πείρω	I pierce, run through; I cleave through
5	Proto-Hellenic	*péryō	—

Every word from Proto-Hellenic *péryō →Every word from Ancient Greek πείρω →Every word from Ancient Greek πόρος →