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circadian

 - 5 dictionary results

cir⋅ca⋅di⋅an

[sur-key-dee-uhn, -kad-ee-, sur-kuh-dee-uhn]
–adjective
noting or pertaining to rhythmic biological cycles recurring at approximately 24-hour intervals.

Origin:
1955–60; < L circā about + di(ēs) day + -an
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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cir·ca·di·an   (sər-kā'dē-ən, -kād'ē-, sûr'kə-dī'ən, -dē'-)   
adj.   Biology
Relating to or exhibiting approximately 24-hour periodicity.

[Latin circā, around; see circa + Latin diēs, day; see dyeu- in Indo-European roots.]
cir·ca'di·an·ly adv.
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Word Origin & History

circadian 
coined 1959 from L. circa "about" + diem, acc. sing. of dies "day" (see diurnal).
Online Etymology Dictionary, © 2001 Douglas Harper
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Medical Dictionary

Main Entry: cir·ca·di·an
Pronunciation: (")s&r-'kad-E-&n, -'kAd-; "s&r-k&-'dI-&n, -'dE-
Function: adjective
: being,having, characterized by, or occurring in approximately 24-hour periods or cycles (as of biological activity or function) <circadian oscillations> <circadian periodicity><circadian rhythms in behavior or physiological activity> —compare INFRADIAN, ULTRADIAN
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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Medical Dictionary

circadian cir·ca·di·an (sər-kā'dē-ən, -kād'ē-, sûr'kə-dī'ən, -dē'-)
adj.
Relating to biological variations or rhythms with a cycle of about 24 hours.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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