What do we call a material that will not ignite or burn when exposed to fire?

The term used to describe a material that will not ignite or burn when exposed to fire is "noncombustible material." Noncombustible materials are those that, under specified conditions of use, do not sustain combustion, meaning they do not ignite and produce a flame or contribute to the spread of fire. This property is crucial in construction and fire safety as it helps to prevent the spread of fire and provides a measure of safety in buildings and structures.

While fire-retardant materials are designed to slow down the spread of fire or reduce the production of flames, they can still burn under certain conditions. Nonflammable material can imply a lack of flammability, but it does not carry the same specific connotation or tested standards as noncombustible material. Reactive materials, on the other hand, refer to substances that can undergo a chemical change that might produce heat and flames, making them relevant in discussions of hazards, but not in the context of materials resistant to ignition. Thus, the most accurate label for materials that do not ignite or burn is noncombustible.