biological clock

[ bahy-uh-loj-i-kuhl klok ]

noun

, Physiology.

1. Also called bod·y clock [bod, -ee klok]. an innate mechanism of the body that regulates its periodic cycles or biorhythms, such as the sleep-wake cycle. chronotype ( def ), circadian ( def ).
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!

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

biological clock

/ 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.

biological clock

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 .

Notes

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.

Word History and Origins

Origin of biological clock¹

First recorded in 1950–55

Example Sentences

I've never had any regrets and must have not come equipped with the mythical biological clock.

From The Daily Beast

Before the fertility revolution, it was the alarm on the biological clock that rang at about age 35.

From The Daily Beast

She now made plans to marry and have a child just as her biological clock was ticking toward never.

From The Daily Beast

"Stress is basically a biological clock," Singer told The Daily Beast.

From The Daily Beast

Related Words

• circadian rhythm