Could lat. circus 'circle' (< gr. κίρκος) and κύκλος 'cycle' be related?

Question

It is well established that the Latin word circus 'circle' is a loanword from Greek κίρκος kírkos 'circle, ring'. But it seems that κίρκος is of uncertain origin. One possibility is that κίρκος would be a loanword or an irregular development related to κύκλος kúklos 'circle' (< Proto-Indo-European *kʷkʷlos 'circle'). What about the posibility that in some Indo-European neighboring Greek (Old Macedonian, Peonian, Thracian, ...) we would have had the development:

(1) pIE *kʷekʷlos > *kʷekʷros > *kʷerkʷos -> κίρκος

Do you see any reason why this highly speculative conjecture could be incorrect at any point?

Answer 1

It's obviously impossible to disprove an etymology based on an unknown language, but here are some things to note:

1. The Greek word in question (assuming it's one word -- the range of meanings is very broad) has two forms, κίρκος and κρίκος. The meaning "circle" or "racecourse" appears to be late; Chantraine (in his etymological dictionary of Greek) suggests that, though Lat. circus itself is probably a borrowing of this Greek word, the "circle" meaning developed in Latin and was then re-borrowed into Greek.

2. Chantraine and Beekes both think the earlier form was κρίκος. If so, that would necessitate one additional metathesis in your etymology, or else a different derivation like *kʷekʷros > *kʷrekʷos.

3. Based on the meanings of the reflexes, PIE *kʷekʷlos is AFAIK generally thought to have meant specifically "wheel" rather than "circle". But of course the semantic development "wheel > circle" is easy (it seems to have happened with Greek κύκλος).