Rifle

A rifle is a long-barreled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves cut into the bore wall [BabelNet]. It is a type of gun with a long barrel, fired from the shoulder, and designed to be accurate at long distances [Cambridge online dictionary].

A rifle is a firearm with a rifled bore, having shallow spiral grooves cut inside the barrel to impart a spin to the projectile, thus stabilizing it in flight. A rifled barrel imparts much greater accuracy to a projectile as compared with a smoothbore barrel.
Rifled firearms date back to at least the 15th century. As some of the earliest had straight rather than spiral grooves, it is thought that the initial purpose may have been to receive the powder residue or fouling, which was a problem with early firearms. Gun makers soon discovered it. However, the spiral grooves made bullets spin, and that spinning improved their range and accuracy. The effect increased when spherical balls were superseded by somewhat-elongated projectiles [Online Encyclopedia Britannica].

Sources:

Rifle. BabelNet. Retrieved from: https://babelnet.org/synset?id=bn%3A00067785n&orig=rifle&lang=EN.

Rifle. Cambridge online dictionary. Retrieved from: https://dictionary.cambridge.org/dictionary/english/rifle

Rifle. Online Encyclopedia Britannica. Retrieved from: https://www.britannica.com/technology/rifle.