What is Fire Retardant?

Alternative Forms: Flame retardant
Legal Definition
A fire retardant is a substance that reduces flammability of fuels or delays their combustion. This includes chemical agents, but may also include substances that work by physical action, such as cooling the fuels, such as fire-fighting foams and fire-retardant gels. Fire retardants may also be coatings applied to an object, such as a spray retardant to prevent Christmas trees from burning. Fire retardants are commonly used in fire fighting.

Home fires damage about 400,000 homes, and cause approximately 7 billion US dollars in direct damage annually in the United States. Because of the importance of prevention, fire retardation has become a very notable industry.
-- Wikipedia
Legal Definition
Fire retardant (or flame retardant) is a substance added to materials to prevent fire, delay fire, or reduce the combustion.