A revolver is a small gun you hold in one hand. The bullets sit in a round case that turns each time you fire, so the next bullet lines up ready. That turning is why it has this name: the case revolves. Not every handgun is a revolver. Many newer pistols feed bullets from a straight box instead of a turning case. The word was made for this kind of gun; it is not a general name for “anything that spins.” In films and old cowboy stories it is the classic one-handed gun. You will also meet it as a band or album name, borrowed from the gun, not from a door.