English word circadian comes from Latin circus, Latin diem, English -an
| Dictionary entry | Language | Definition |
|---|---|---|
| circus | Latin (lat) | A circular line or orbit; circle, ring. A racecourse or space where games are held, especially one that is round. The spectators in a circus; a circus. |
| diem | Latin (lat) | |
| -an | English (eng) | Appended to nouns to form an agent noun. (When males with a profession are distinguished from females, males are -an, females -(i)enne.). Of or pertaining to; an adjectival suffix appended to various words, often nouns, to make an adjective form. (Often added to words of Latin origin, but also used with words of other origins. When a word ends in a, -n is used instead.). |
| circadian | English (eng) | (biology) of, relating to, or showing rhythmic behaviour with a period of 24 hours; especially of a biological process. |