1. The transfer of property from ecclesiastical to civil possession.
2. A procedure of changing something (art or education or society or morality etc.) so it is no longer under the control or influence of religion.
3. The process of becoming secular; the separation of civil or educational institutions from ecclesiastical control.

Secularization is also defined by some as the process in which mystical, sacred, and otherworldly explanations, outlooks, beliefs, interests, and concerns are replaced by rational, critical evaluations and by pragmatic and utilitarian standards.