A saeculum is a length of time roughly equal to the potential lifetime of a person or, equivalently, the complete renewal of a human population.
The new millennium that Rome entered was called the saeculum novum,[6] a term that received a metaphysical connotation in Christianity, referring to the worldly age (hence "secular").
[7] Roman emperors legitimised their political authority by referring to the saeculum in various media, linked to a golden age of imperial glory.
In response, Christian writers began to define the saeculum as referring to 'this present world', as opposed to the expectation of eternal life in the 'world to come'.
[9] The descendants of Latin saeculum in the Romance languages generally mean "century" (i.e., 100 years): French siècle,[10] Spanish siglo,[11] Portuguese século,[12] Italian secolo,[13] etc.