IPA: /ˌsɜːrkəmˈvʊlʃən/
KK: /sɜrˌkʌmˈvʊlʃən/
A single turn or twist around a central point or axis.
The circumvolution of the spiral staircase made it difficult to see the top from the bottom.
Circumvolution is formed from "circum-" (meaning around) and "volutio" (from Latin, meaning a rolling or turning). The word describes the act of rolling or turning around something.
Think of something moving 'around' ('circum-') in a 'rolling' motion ('volutio') — that's what circumvolution means.