Where does “Cirenaica” come from?

Cirenaica (Portuguese) comes from Latin Cyrenaica, from Ancient Greek Κῡρηναϊκή.

Ancestry of “Cirenaica”, step by step

Step	Language	Word	Meaning
1	Latin	Cyrenaica	—
2	Ancient Greek	Κῡρηναϊκή	—

Cirenaica — Etymology, Origin & Word History | Etymology Explorer