Where does “κυκλικός” come from?

κυκλικός (Ancient Greek) comes from Ancient Greek κύκλος, from Proto-Indo-European kʷékʷlos, from Proto-Indo-European kʷel- — to turn.

Ancestry of “κυκλικός”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	κύκλος	circle, ring; Any circular object, such as a...
2	Proto-Indo-European	kʷékʷlos	wheel; circle
3	Proto-Indo-European	kʷel-	to turn

κυκλικός — Etymology, Origin & Word History | Etymology Explorer