gatling gun
A type of heavy machine gun with multiple rotating barrels.
The original Gatling gun was invented by Richard Jordan Gatling and first used in the American Civil War. Though not automatic in operation, it was a direct ancestor of today's machine guns. Gatling-style rotating barrels are still used in modern heavy machine guns such as the M61 Vulcan, the GAU-8, and the M134 Minigun.
On Danbooru, Gatling gun refers to any kind of heavy machine gun with multiple rotating barrels, not just the original Civil War-era Gatling gun.