What is the term for materials that can spontaneously combust?

The term for materials that can spontaneously combust is pyrophoric materials. These substances have the ability to ignite spontaneously in air at or below room temperature, which means they do not require an external ignition source such as a flame or spark to catch fire. The ability of pyrophoric materials to ignite readily poses significant hazards in handling, storage, and transportation contexts, particularly in environments where they can come into contact with oxygen.

In contrast, volatile materials are characterized by their ability to vaporize quickly at room temperature, which might lead to flammability but does not guarantee spontaneous combustion. Corrosive materials can cause damage to living tissue or materials upon contact but do not necessarily have combustion properties. Reactive materials can undergo a chemical reaction under certain conditions, but not all reactive materials will spontaneously ignite. Therefore, pyrophoric accurately identifies those materials that can ignite on their own without external ignition sources.