Smooth-bore refers to a type of gun barrel that has a smooth inner surface. Synonyms for this term include non-rifled, unrifled, plain bore, and conventional bore. These terms indicate that the barrel lacks the spiral grooves that are characteristic of a rifled barrel, which would impart spin to a bullet or projectile. A smooth-bore barrel is typically used for shotguns, artillery, and certain firearms that require a wider range of projectiles. While smooth-bore guns lack the accuracy of rifled barrels, they are often preferred for their ability to fire multiple projectiles simultaneously, making them useful for hunting, sport shooting, and military applications.