1. substances that slow down or delay a chemical reaction or process
Usage: technical; chemistry
2. devices or mechanisms that reduce speed or slow down movement
Usage: mechanical; automotive

Examples

• The concrete mix included retarders to slow the setting process in hot weather.
• Chemical retarders are added to prevent premature curing of the material.
• The truck’s engine retarders helped control speed on the steep downhill grade.
• Fire retarders in the fabric help prevent rapid flame spread.
• Speed retarders were installed on the residential street to calm traffic.
• The laboratory tested various retarders to find the most effective one.