Saeculum

A saeculum is a length of time roughly equal to the lifetime of a person, or about 90 years. It can be divided into four "seasons" of approximately 22 years each; these seasons represent youth, rising adulthood, midlife, and old age.

The ancient Romans held their Olympics once a saeculum, guaranteeing that the Olympic would occur at some point in the average Roman's life. By the second century B.C., Roman historians were using the saeculum to periodize their chronicles and track wars.

See also generation.