Abstract
The meaning of ‘secular’ in the scientific use of ‘secular trend’, ‘secular variation’, and similar terms is a topic that merits historical investigation. The scientific meaning for ‘secular’ has an origin and independent role apart from both religion and secularization. Fields in the social sciences, life sciences, and natural sciences have been using the concepts of ‘secular trend’ and ‘secular variation’ for almost two centuries. The field of economics was the first among the social sciences, while epidemiology was the first in the life sciences. Both disciplines adapted the use of ‘secular trend’ and ‘secular variation’ from the earth sciences, which borrowed the idea of ‘secular’ from astronomy. Early astronomical texts first used ‘secular’ to describe ‘secular inequalities’ and ‘secular variations’ in long-term patterns to celestial motions. Astronomers had found saeculum to be a convenient Latin word from ancient Rome to refer to a century’s duration. This article recounts the intellectual history of the scientific uses, which continue to lack a relationship with anything religious to the present day.