“In Roman conceptions of time, the saeculum became the longest fixed interval, calculated as a period of 100 or 110 years (as opposed to, e.g., a lustrum of only five years; cf. “census”). The term originally indicated a “generation” or “lifetime,” but greater significance developed through its association with the Ludi Saeculares (Secular Games), which were performed to celebrate the advent of a new saeculum in Rome. Through the Secular Games, the emperor advertised his role in establishing his dynasty and ushering in an age of peace; emperors who wished to capitalize on this expression of authority made official references to the saeculum in coinage and inscriptions if they were unable to hold the Games during their reigns, thus creating a close link between the saeculum, imperial families, and political control. In Late Antiquity, the Christianization of the empire led to other usages. Because of its association with political power, the saeculum came to signify “the present age of the world,” in contrast with an eternal, heavenly realm; it could also be applied to a new, Christian era.”

Source:
Bilynskyj Dunning, S. (2017, November 20). saeculum. Oxford Classical Dictionary. Retrieved 9 Mar. 2025, from https://oxfordre.com/classics/view/10.1093/acrefore/9780199381135.001.0001/acrefore-9780199381135-e-8233.