Improvement (or an intended improvement) in the existing form or condition of institutions or practices etc.; intended to make a striking change for the better in social or political or religious affairs WordNet 3.0 & Open English WordNet

An improvement (or an intended improvement) in the existing form or condition of institutions or practices, etc.; intended to make a striking change for the better in social, political or religious affairs or in the conduct of persons or operation of organizations. Wiktionary

Improvement in the condition of institutions. Wiktionary (translation)