biological clock
noun1
Biology, Natural sciences Any of several mechanisms that regulate the periodicity of biological functions, such as the circadian rhythm.
- 2005 US Department of Health - Your guide to healthy sleep Your biological clock is actually a tiny bundle of cells in your brain that responds to light signals received through your eyes.
2
Figuratively The perceived time limit of human fertility, especially for women, evoking pressure to conceive children before reproductive ability declines with age.
- Her biological clock is ticking.
- Take Linda, a thirty-nine-year-old newscaster who relished her career but began to hear the alarm ringing on her biological clock.1994, Rugh Winter, Bonnie Eaker-Weil, Adultery, the Forgivable Sin:
- Derived terms
- tick-tock biological clock
- Related terms
- biorhythm, circadian rhythm