'secularize' originates from Latin, specifically from 'saecularis' and the noun 'saeculum', where 'saeculum' meant 'age' or 'generation', and the verb-forming suffix '-ize' (via Greek/Latin) meant 'to make or render'.

'secularize' developed from Medieval Latin 'saecularizare' and later appeared in modern European languages such as French ('séculariser'), eventually entering English as 'secularize'.

Initially it was used in contexts of transferring church property or authority into worldly, nonreligious hands; over time it broadened to mean making something nonreligious or removing religious character more generally.