retardant

American  

[ri-tahr-dnt] / rɪˈtɑr dnt /

noun

Chemistry.

1. any substance capable of reducing the speed of a given reaction.

---

adjective

1. retarding or tending to retard (usually used in combination).

   fire-retardant construction materials.

retardant British  

/ rɪˈtɑːdənt /

noun

1. a substance that reduces the rate of a chemical reaction

---

adjective

1. having a slowing effect

Other Word Forms

• retardance noun
• retardancy noun

Etymology

Origin of retardant

First recorded in 1635–45; retard + -ant

Example Sentences

Among the synthetic products, 19 claimed to be flame retardant, three were labeled water resistant, nine advertised heat resistance, and three promoted "green" claims such as "no PVC" or "non-toxic."

From Science Daily • Feb. 19, 2026

He says if the foam had been fire retardant it would have smouldered, not burned.

From BBC • Jan. 17, 2026

Fire crews typically use tanker trucks to bring water, and also rely on helicopters and planes to drop water and retardant on fires.

From Los Angeles Times • Dec. 17, 2025

"What that pressure is doing is, it's forcing the fire retardant into the very core of the timber," says Mr McCann.

From BBC • Nov. 6, 2025

The firefighters now directed all their attention to adjacent buildings, hosing down nearby roofs with fire retardant.

From "Scythe" by Neal Shusterman