- The backpressure in an internal-combustion engine or a boiler.
- Powder residue that is released upon automatic ejection of a spent cartridge or shell from a firearm.
- The effect caused by recirculation into the source country of disinformation previously planted abroad by that country's intelligence service in an effort to mislead the government of another country.
- Τhe escape, to the rear and under pressure, of gases formed during the firing of a weapon. Blowback may be caused by a defective breech mechanism, a ruptured cartridge case, or a faulty primer.
- Α type of weapon operation in which the force of expanding gases acting to the rear against the face of the bolt furnishes all the energy required to initiate the complete cycle of operation.