1. the process of returning to a former or less advanced state; decline or deterioration

Examples

• The patient showed signs of retrogression after stopping the medication.
• Economic retrogression followed the collapse of the main industry.
• The country experienced political retrogression under the new regime.
• Scientists observed retrogression in the coral reef’s health over several years.
• The team’s performance showed clear retrogression compared to last season.
• Educational retrogression became evident when test scores dropped significantly.