What is a cannon?

A cannon is generally understood to be a large firearm that uses a substantial bore to launch projectiles at high speeds, typically utilizing explosive propellants. The definition aligns best with the description of a shell-firing gun, as cannons are designed to fire projectiles such as shells over long distances. These weapons have historically been used in warfare and can deliver significant firepower over a considerable range, effectively fitting the criteria of a shell-firing gun.

In comparing this to the other options, a gun primarily for hunting might refer to smaller firearms designed for shooting game, which is more associated with rifles and shotguns, rather than a cannon's larger caliber design. A type of artillery used for long-range fire closely resembles the characteristics of a cannon, but it may encompass a broader category that includes different types of artillery, including howitzers and mortars, which may not fit the traditional definition of a cannon. Lastly, a grenade-launching weapon is distinctly different as it typically refers to smaller, portable devices designed to launch grenades rather than a fixed artillery piece like a cannon.