circadian
Americanadjective
adjective
Etymology
Origin of circadian
First recorded in 1955–60; from circā “about” + Latin di(ēs) “day” + -an ( def. ); see circa ( def. )
Explanation
Something that's circadian happens on a regular, daily basis. Your body's circadian rhythm is made up of processes that occur regularly every 24 hours. You'll find the word circadian in biology class, or your anatomy and physiology textbook, because it describes a biological process in the human body, as well as in other organisms. Your cycle of sleep, for example, happens on a circadian schedule — approximately every 24 hours, you become tired enough to lie down and close your eyes, a built-in rhythm that's affected somewhat by light. Circadian comes from Latin roots, circa, "about," and diem, "day."
Vocabulary lists containing circadian
November Words
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This Week in Words: Current Events Vocab for March 27–April 2, 2021
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This Week in Words: Current Events Vocab for November 10–November 16, 2024
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Shapses said she wants to better understand issues such as circadian rhythm, inflammation, metabolic health, and the biochemical issues that help the body sense and respond to food.
From MarketWatch ● Jul. 27, 2026
The pineal gland produces melatonin, a hormone that helps control the circadian rhythm.
From Science Daily ● Jul. 26, 2026
“When you have a more robust light signal early in the morning, that will help keep your internal circadian system synchronized to the day.”
From Los Angeles Times ● Jul. 14, 2026
Light sets our circadian rhythm, or 24-hour body clock, which tells us when to wake up.
From BBC ● Jul. 6, 2026
Called the circadian rhythm, this clock is geared to the place where you have been living recently.
From "Flying to the Moon: An Astronaut's Story" by Michael Collins
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
