Etymology

circadian

C3I1R1C3A1D2I1A1N1

Today it means: Of, relating to, or showing rhythmic behaviour with a period of approximately 24 hours; especially of a biological process. Full definition →

Latin diēs ← Proto-Italic *djous ← Proto-Indo-European *dyḗws
Ask AI about its historyChatGPTClaudePerplexityGoogle AIGrok

The story

  1. Proto-Indo-European*(s)ker-
  2. Ancient Greekκίρκος (kírkos)
  3. Latincircus
  4. Latincircum
  5. Latincircā
  6. Proto-Indo-European*dyew-
  7. Proto-Indo-European*dyḗws
  8. Proto-Italic*djous
  9. Latindiēs
  10. English todaycircadian

From Latin circā (“around”) + diēs (“day”) + English -an. Compare circannual.

Etymology from Wiktionary, CC BY-SA 4.0.