Where does “psi” come from?

psi (Latin) comes from Ancient Greek ψεῖ — psi, the name for the twenty-fourth letter Ψ, ψ...

Ancestry of “psi”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	ψεῖ	psi, the name for the twenty-fourth letter Ψ, ψ...