A semi-automatic pistol is a type of pistol that is semiautomatic, that is it uses the energy of the fired cartridge to cycle the action of the firearm and advance the next available cartridge into position for firing. One round is fired each time the trigger of a semi-automatic pistol is pulled; the pistol's "disconnector" ensures this behavior. Additional terms sometimes used as synonyms for a semi-automatic pistol are automatic pistol, self-loading pistol, autopistol, and autoloading pistol.