1. a substance that slows down or prevents a process, especially burning or chemical reaction

1. serving to slow down or prevent a process

Examples

• The firefighters used a flame retardant to stop the wildfire from spreading.
• Fire retardant chemicals are added to children’s pajamas for safety.
• The building materials were treated with a fire retardant coating.
• Scientists developed a new rust retardant for metal surfaces.
• The retardant foam quickly extinguished the aircraft fire.
• Water can act as a retardant in certain chemical reactions.