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biological clock

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noun Physiology.
  1. an innate mechanism of the body that regulates its rhythmic and periodic cycles, as that of sleeping and waking.

Origin of biological clock

First recorded in 1950–55
Also called body clock.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for biological clock

biological clock

noun
  1. an inherent periodicity in the physiological processes of living organisms that is not dependent on the periodicity of external factors
  2. the hypothetical mechanism responsible for this periodicity
See also circadian
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

biological clock in Medicine

biological clock

n.
  1. An innate mechanism in living organisms that controls the periodicity or rhythm of various physiological functions or activities.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

biological clock in Science

biological clock

[bī′ə-lŏjĭ-kəl]
  1. An internal system that controls an organism's circadian rhythms, the cycles of behavior that occur regularly in a day. In mammals, the biological clock is located near the point in the brain where the two optic nerves cross. In many birds, the biological clock is located in the pineal gland. In protists and fungi, the individual cells themselves regulate circadian rhythms.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

biological clock in Culture

biological clock

The innate rhythm of behavior and body activity in living things. A twenty-four-hour cycle of body activity, which operates in some organisms, is called the circadian rhythm.

Note

Although the term biological clock refers to all innate timing mechanisms, it is often used when describing certain body functions that are subject to this rhythm, such as the loss of fertility with age.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.