| circadian | (adj) of or relating to biological processes occurring at 24-hour intervals, Example: circadian rhythms |
| circadian rhythm | (n) a daily cycle of activity observed in many living organisms |
| circaea | (n) enchanter's nightshade, Syn. genus Circaea |
| circaea lutetiana | (n) tall evening primrose with inconspicuous flowers |
| circaetus | (n) harrier eagles, Syn. genus Circaetus |
| circassian | (n) a member of the Sunni Muslim people living in northwestern Caucasia |
| circassian | (n) a mostly Sunni Muslim community living in northwestern Caucasia |
| circassian | (n) a northern Caucasian language spoken by the Circassian |