A revolver cannon is a type of autocannon, commonly used as an aircraft gun. It uses a cylinder with multiple chambers, similar to those of a revolver handgun, to speed up the loading-firing-ejection cycle. Some examples are also power-driven, to further speed the loading process. Unlike a rotary cannon, a revolver cannon only has a single barrel, so its spun weight is lower. Automatic revolver cannons have been produced by many different manufacturers.

An autocannon, automatic cannon or machine cannon is a fully automatic gun that is capable of rapid-firing large-caliber armour-piercing, explosive or incendiary shells, as opposed to the smaller-caliber kinetic projectiles (bullets) fired by a machine gun. Autocannons have a longer effective range and greater terminal performance than machine guns, due to the use of larger/heavier munitions, but are usually smaller than tank guns, howitzers, field guns, or other artillery. When used on its own, the word "autocannon" typically indicates a non-rotary weapon with a single barrel. When multiple rotating barrels are involved, such a weapon is referred to as a "rotary autocannon" or occasionally "rotary cannon", for short.