1. a substance that slows down a chemical reaction or process
Usage: chemistry; technical
2. a device that slows down or delays something
Usage: technical

Examples

• The concrete retarder prevented the mixture from setting too quickly in hot weather.
• Fire retarders are added to fabrics to slow the spread of flames.
• The chemical retarder gave workers more time to finish the project.
• Heavy trucks use engine retarders to slow down on steep hills.
• The paint retarder extended the drying time for better blending.
• Flame retarders in furniture help prevent fires from spreading rapidly.