Periodicity

**Definition:** The tendency of a phenomenon to recur at regular intervals; in biological systems, the recurrence of certain activities (including hormonal, cellular, neural) may be annual, seasonal, monthly, daily, or more frequently (ultradian).

**Tree numbers:** - G01.910.645 - G07.180.562

**Synonyms:** - Biorhythms - Bioperiodicity - Biological Rhythms - Cyclicity - Rhythmicity