noun /ˈsɜː(ɹ).kjʊˌleɪ.ʃən,ˈsɝkjʊˌleɪʃən/
a) The act of moving in a circle, or in a course which brings the moving body to the place where its motion began.
b) The act of passing from place to place or person to person; free diffusion; transmission.
Wikipedia foundation.