Multigun is a unique type of ground ranged weapon in Xenoblade Chronicles X, exclusive to the Delta Bliss. It is a cross between a cannon, a missile launcher, and a rifle. It was part of Yelv's DLC in the Japanese version.
It is classified as a "Special Weapon" in certain menus such as the Scout Console. Any class can equip a multigun, and equipping a multigun provides its own ranged weapon arts (the user is unable to use ranged weapon arts from their own classes).