Where does “Poseidon” come from?

Poseidon (German) comes from Ancient Greek Ποσειδῶν, from Latin Posīdōn.

Ancestry of “Poseidon”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	Ποσειδῶν	Poseidon, god of earthquakes
2	Latin	Posīdōn	—