circadian

adjective

cir·​ca·​di·​an sər-ˈkā-dē-ən How to pronounce circadian (audio)
: being, having, characterized by, or occurring in approximately 24-hour periods or cycles (as of biological activity or function)
circadian rhythms in activity

Did you know?

In 1959, a scientist formed the word circadian from the Latin words circa ("about") and dies ("day"), and it caught on quickly. Most often, it's seen and heard in the term circadian rhythm, which refers to the inherent cycle of about 24 hours that appears to control various biological processes, such as sleep, wakefulness, and digestive activity. If you want to impress your friends, you can also use the term circadian dysrhythmia, a fancy synonym of jet lag.

Examples of circadian in a Sentence

Recent Examples on the Web According to Choose Cherries, preliminary new research found that getting 8 ounces of tart cherry juice twice a day (in the morning and at night) can be optimal for regulating your circadian rhythm and the sleep-wake cycle. Sharon Greenthal, Better Homes & Gardens, 24 May 2024 Lured by the proximity to campus, students in windowless rooms try to cope with abundant room decoration, circadian rhythm LED lighting, mental therapy or medication. Juan Miró, The Conversation, 16 May 2024 See all Example Sentences for circadian 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'circadian.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Latin circa about + dies day + English -an entry 2 — more at deity

First Known Use

1959, in the meaning defined above

Time Traveler
The first known use of circadian was in 1959

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Dictionary Entries Near circadian

Cite this Entry

“Circadian.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/circadian. Accessed 1 Jun. 2024.

Medical Definition

circadian

adjective
: 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

More from Merriam-Webster on circadian

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