Hi, I'm making a glossary as part of a group project, and I need a definition or description of this term. My group-mate swears blind that it is in fact a word, and I've seen it come up in web searches, but I can't for the life of me find anything helpful. Does anybody have any suggestions?

Do you mean circulatory system? Circularity system makes no sense to me.

Agree with Ophiolite - it's a confusion. If you google circularity system but not circulatory you only get a handful (well 1400) answers and first page results all seem to be confusing the two terms. OTOH circulatory system is a very important concept, especially the double circulatory system