Where does “Īsis” come from?

Īsis (Latin) comes from Ancient Greek Ἶσις, from Egyptian ꜣst — Isis.

Ancestry of “Īsis”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	Ἶσις	Isis
2	Egyptian	ꜣst	Isis

Īsis — Etymology, Origin & Word History | Etymology Explorer