"moving through a circuit," c. 1600, of blood, from French circulatoire or directly from Latin circulatorius, from circulator, agent noun from circulare "form a circle," from circulus (see circle (n.)). Circulatory system is recorded from 1862.
circular
circularity
circulate
circulation
circulator
circulatory
circum-
circumambient
circumambulate
circumbendibus
circumcise