The term derringer is a genericized misspelling of the name Deringer, a famous maker of small pocket pistols in the 1800s. Many copies of the original Deringer pistols were made by other gun makers worldwide, and the name was often misspelled; this misspelling soon became a generic term for any pocket pistol. The original Deringer pistol was a single shot muzzleloading pistol; with the advent of cartridge firearms, pistols began to be produced in the modern form still knows as a "derringer".

A derringer is intended to be the smallest useable handgun of a given caliber. Derringers are not repeating firearms--repeating mechanism such as used on semiautomatic handguns or revolvers would add significant bulk to the gun, defeating the purpose. The original cartridge derringers held only a single round, usually a pinfire or rimfire cartridge, usually around a .40 caliber , and the barrel pivoted sidways on the frame to allow access to the breech for reloading. The famous Remington derringer design doubled the capacity, while maintaining the compact size, by adding a second barrel on top of the first, and pivoting the barrels upwards to reload. Each barrel then held one round, and a cam on the hammer alternated between top and bottom barrels. The Remington derringer was orignally sold in .41 Rimfire caliber, and achieved wide popularity.

Even with the advent of smaller, higher powered cartridges made possible by the use of smokeless powder rather than the black powder used in the 1800s and before, the classic Remington design is still popular; a Remington patter derringer in .38 Special is still smaller than the most compact .25 ACP semiautomatic, and provides far superior terminal ballistic performance in its 2 shots than the .25 ACP does with 6 or 7. While the classic Remington design is a single action, manufacturers have also made double action derringers, including some 4 shot models, with the barrels stacked in a 2 x 2 block. The "COP" derringer, made in Torrance, CA, provided 4 shots of .357 Magnum, still in a package not much larger than a .25 ACP automatic, and significantly more compact than a similar revolver.

A related design, often grouped with derringers since it fits nowhere else, is the Semmerling pistol. It is a 5 shot, .45 ACP pistol that is a manual repeater; the barrel mechanism is manually pulled forward to eject the fired round, then pushed back to chamber the next round. These pistols were originally built for the U. S. Army, and the few that are available on the civilian market are highly sought after due to their unique combination if high power, large capacity, and tiny size. Another military pistol that is truly a derringer design is the Liberator Pistol, a .45 ACP insurgency weapon dropped behing Axis lines in WWII.