When is a circus not a circus?

For those who don't know (probably no-one then) the English dictionary definition of a circus is:

...a large public entertainment, typically presented in one or more very large tents or in an outdoor or indoor arena, featuring exhibitions of pageantry, feats of skill and daring, performing animals, etc., interspersed throughout with the slapstick antics of clowns.

So nowhere could I find a definition that related to the convergence of roads to a central point providing exits to all points north, south, east and west. There are some references to the Greek word for ring, kirkos. Sounds plausible.

Personally, I think it's to do with the clowns who race around with total disregard to all and sundry and, like the guy in this image, those who find seats where they can to sit and be entertained by these clowns.