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circadian

[sur-key-dee-uh n, -kad-ee-, sur-kuh-dee-uh n]
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adjective
  1. noting or pertaining to rhythmic biological cycles recurring at approximately 24-hour intervals.
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Origin of circadian

1955–60; < Latin circā about + di(ēs) day + -an
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words

regularly, often, periodic, constantly, regular, routine, everyday, day-to-day, ordinary, commonplace, common, quotidian, cyclic, circadian, diurnal

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British Dictionary definitions for circadian

circadian

adjective
  1. of or relating to biological processes that occur regularly at about 24-hour intervals, even in the absence of periodicity in the environmentSee also biological clock
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Word Origin

C20: from Latin circa about + diēs day
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for circadian

adj.

coined 1959 from Latin circa "about" (see circa) + diem, accusative singular of dies "day" (see diurnal). The original use is in circadian rhythm.

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Online Etymology Dictionary, © 2010 Douglas Harper

circadian in Medicine

circadian

(sər-kādē-ən, -kădē-, sûr′kə-dīən, -dē-)
adj.
  1. Relating to biological variations or rhythms with a cycle of about 24 hours.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.