I have enjoyed considering eddies over the years and used the word in a poem a few years back.

However, I only recently learned that eddies are generally circular. Why so? My own visualization of eddies hadn't been of circular ones.

And a second definition that is just great:

"a contrary or circular current (as of thought or policy) " MW

A contrary thought! Contrary thoughts! Contrary policies! Wow! Why haven't I read this word used this way constantly?