Drop Safe
A firearm designed to not discharge if dropped onto a hard surface.
A drop safe firearm has internal mechanisms — typically a firing pin block and an inertial firing pin — that prevent the firing pin from striking the primer unless the trigger is fully pulled, even if the gun is dropped on its muzzle or hammer. Modern designs are universally drop safe by design and by drop-test. Historical designs (older 1911s, old single-action revolvers carried with all chambers loaded) often were not.