I don't know that there is a legislated definition for these in Delaware. Generally the "long gun" is meaning a rifle or shotgun( they can be single shot, semi-automatic, bolt action or pump) designed to be fired from the shoulder. A "handgun" or a "pistol" is generally defined as a gun designed to be held and fired with one hand. A revolver is a pistol with a revolving cylinder type ammo feed. Semi-automatic is usually a magazine feed pistol able to fire multiple rounds of ammo in a short amount of time. There are also Derringers that are designed to fire one or in some cases a few rounds, and designed to be carried in a concealed manor, usually used at close range, as they are not very accurate or powerful at a distance.