What is "long gun"

n. A firearm, such as a shotgun or rifle, which is fired while braced against the shoulder.

A long gun is a category of firearms and cannons with longer barrels than other classes. In small arms, a long gun is generally designed to be fired braced against the shoulder, in contrast to a handgun, but may include mounted firearms while in artillery a long gun would be contrasted with a howitzer or carronade.