Final answer:
A propellant that deflagrates is a low explosive, which is a type of explosive that combusts rapidly but at subsonic speeds, used to create pushing force rather than shatter objects.
Step-by-step explanation:
If a propellant deflagrates, it is considered a low explosive. Deflagration is a term used to describe a rapid combustion that moves through a material at less than the speed of sound. This type of explosive reaction describes low explosives, which are fuels that burn to create a pushing force rather than a shattering one. Low explosives are commonly used as propellants in firearms, fireworks, and rocketry. An example of the use of low explosives is in certain types of rocket engines, where the explosion resulting from the propellant generates thrust.