The UFC’s eight-sided fighting enclosure is called the Octagon.
The Octagon is a fenced competition area with eight sides, created to give UFC bouts a distinctive visual identity while allowing fighters to move, grapple, and strike. Although the word is commonly used as a proper name for the UFC cage, the actual structure has changed in dimensions and presentation over the organization’s history.
The original UFC events used a similar eight-sided enclosure, but early events had fewer standardized regulations than modern UFC cards. Today, the Octagon is strongly associated with the promotion and appears in its branding, broadcasts, and event venues.
A common mix-up is calling it simply a boxing ring. A ring uses ropes and generally has four sides, while the UFC’s Octagon uses fencing and has eight sides. The word also appears in other combat-sports contexts, but it is most closely identified with the UFC.