saeculum
A cyclical period of time, roughly equal to the time needed for the complete renewal of a human population: — Any of a sequence of ages (periods of time) such that each age ends with the death of the last person remaining alive since its beginning, and the end of an age marks the beginning of the next.
historical
According to legend, the gods had allotted a certain number of saecula to every people or civilization; the Etruscans, for example, had been given ten saecula.
A cyclical period of time, roughly equal to the time needed for the complete renewal of a human population: — Any of a sequence of ages of set length, used to periodise chronicles and track wars.
historical
At the time of the reign of emperor Augustus, the Romans decided that a saeculum was 110 years.
An approximately 85-year cycle in Strauss-Howe generational theory, a highly controversial sociological theory that postulates that zeitgeist and popular cultural values exist along recurring cycles.
Despite skepticism regarding the degree of forecasting, the authors' presentation of historical events is comprehensive and arguments for their organization into a cyclical method of four era saeculums convincing.
Where it comes from
Learned borrowing from Latin saeculum. Doublet of secle.
Adapted from the Wiktionary entry saeculum (CC BY-SA 4.0).