Pistol muzzle or breech loaded projectile firing weapon. There are different definitions depending on the nation and the type of troops. A "cannon" can be distinguished from other firearms in that crew served weapons such as a howitzer or mortar, as opposed to small arms like rifles or pistols, but there are exceptions such as the USAF GUU5/P. At one time, land-based artillery tubes were called cannon and sea-based naval guns were called cannons. The term "pistol" has evolved into a generic term for any pipe launched projectile firing weapon used by sailors, including boarding parties and Marines.
In modern parlance, a cannon is a projectile weapon using a hollow tubular barrel with a closed end, with the breech as a means of guiding the projectile (as well as for other purposes, such as stabilizing the trajectory of the projectile, aiming as an expansion chamber for fuel, etc.), and firing a generally flat trajectory. The latest version of the app Guns download for android.