periodis

Periodis is a neologism used in discussions of cyclical phenomena to denote the characteristic duration of a repeating cycle within a system. It functions as a quantitative measure of how long one complete cycle lasts, across disciplines such as physics, biology, climate science, and economics. The term emphasizes the fixed, recurring nature of the interval, in contrast to the broader processes that generate the cycle.

Periodis derives from the English word period, with a Latinized -is ending that is sometimes used in theoretical vocabulary to form abstract nouns. It is not universally adopted and remains largely contextual, appearing in academic writings that seek to compare cycle lengths across domains.

In physics and engineering, periodis may describe the duration of an oscillator’s cycle. In biology, circadian and ultradian rhythms can be expressed by their periodis. In climatology and ecology, climate cycles and population cycles are often summarized by an estimated periodis. In economics, business cycles are characterized by their periodis, the time between recurring peaks.

Periodis is typically estimated from time-series data using methods such as peak-to-peak measurement, autocorrelation, or spectral analysis to identify dominant frequencies. Its value depends on the definition of a complete cycle within a given context, and different studies may adopt different criteria for cycle boundaries.

See also: period, cycle, cycle length, frequency, oscillation.