Where does “Κως” come from?

Κως (Greek) comes from Ancient Greek Κῶς, from Hebrew כוס, from Arabic كُسّ.

Ancestry of “Κως”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	Κῶς	—
2	Hebrew	כוס	A cup, glass, tumbler; little owl; A pussy
3	Arabic	كُسّ	—

Κως — Etymology, Origin & Word History | Etymology Explorer