Words: blowback
Part of speech: n
Definition: Blowback is a system of operation for self-loading firearms that obtains energy from the motion of the cartridge case as it is pushed to the rear by expanding gases created by the ignition of the propellant charge.
Example: In most actions that use blowback operation, the breech is not locked mechanically at the time of firing: the inertia of the bolt and recoil spring(s), relative to the weight of the bullet, delays opening of the breech until the bullet has left the barrel