Spontaneously Combustible is the materials which can ignite without any flame, spark, heat, or other ignition source by heat retained from processing or any reaction resulting in ignition temperature: spontaneous combustion are caused by spontaneous heating, pyrophoricity, and hypergolic reactions.
Reference Definition by Aiche.org: Spontaneously Combustible means capable of igniting and burning in air without the presence of an ignition source. Pyrophoric materials are spontaneously combustible, although some pyrophorics require the presence of a minimum amount of moisture (humidity) to spontaneously ignite. Other spontaneously combustible substances and mixtures may require more time or an insulating environment to self-heat to the point of ignition.
