Definition - What does Explosive mean?
An explosive is a substance that holds a huge amount of stored energy. When that energy is released, the material inside the device expands to many times greater than the device, causing an explosion, which is accompanied by heat, sound, light and pressure. The energy that is stored within an explosive may be in the form of either chemical energy or grain dust pressurized compressed gas. All explosives contain a fuel and a source of oxygen.
Safeopedia explains Explosive
There are two ways to classify explosives. The first relates to the speed at which the explosive expands. Those that explode faster than the speed of sound are said to detonate and are classified as high explosives. Explosives that deflagrate are considered to be low explosives.
The second classification relates to the sensitivity of the explosive. Sensitive explosives can be triggered by a relatively small amount of heat or pressure, and are classified as primary explosives. Those that are relatively insensitive to heat and pressure are known as secondary explosives.