biological clock

American  

[bahy-uh-loj-i-kuhl klok] / ˈbaɪ əˌlɒdʒ ɪ kəl ˈklɒk /

noun

Physiology.

1. Also called body clock.  an innate mechanism of the body that regulates its periodic cycles or biorhythms, such as the sleep-wake cycle.

2. an innate mechanism regulating the passage of an organism through the natural stages of its life, especially with reference to the reproductive stage of a woman's or man's life or the approaching end of this stage.

   My biological clock is ticking, but I don't feel ready to have kids!

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biological clock British  

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

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biological clock Scientific  

/ bī′ə-lŏj′ĭ-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.

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biological clock Cultural  

1. 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.

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Discover More

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.

Etymology

Origin of biological clock

First recorded in 1950–55

Example Sentences

See Examples For:

biological clock

Women’s expanded education and opportunity spread that window across three decades, which raises the odds of running out the biological clock while still looking for a suitable mate.

From The Wall Street Journal ● Jun. 6, 2026

She argues that switching to daylight-saving time ultimately plays havoc with our circadian rhythm — that is, our internal biological clock.

From MarketWatch ● Mar. 6, 2026

“We’re taking a comprehensive approach to this study, looking at body composition, the epigenome or biological clock, the microbiome and the brain,” said Christopher Gardner, a nutrition scientist at Stanford University.

From Salon ● Jan. 4, 2024

Both evolutionary theories and psychological research on the "biological clock" would have suggested a later decline, namely between the ages of 40 and 50, when women approach the end of their reproductive phase.

From Science Daily ● Dec. 12, 2023

There were certain events in Odessa that had become time- honored traditions, essential elements in the biological clock of the town.

From "Friday Night Lights: A Town, A Team, And A Dream" by H.G. Bissinger

Related Words

• circadian rhythm