circadian

cir·ca·di·an

adj
\(ˌ)sər-ˈkad-ē-ən, -ˈkād-; ˌsər-kə-ˈdī-ən, -ˈdē-\

Definition of CIRCADIAN

: being, having, characterized by, or occurring in approximately 24-hour periods or cycles (as of biological activity or function) <circadian periodicity> <circadian rhythms in behavior or physiological activity>—compare infradian, ultradian