A wrestling ring is a location in which is meant for wrestling to take place in the sport of professional wrestling. While most wrestling rings are square in shape, some games like TNA Impact or Lucha Libre AAA: Heroes Del Ring feature a 6 sided ring.
Origin of the term 'Squared circle'
Although the term ‘wrestling’ is most closely associated with Greek wrestling that goes as far back as 700 BC, the sport of wrestling has made its appearance in cultures all over the world; from in Egyptian art to Sumerian literature, and from Babylonia to Chinese and Indian civilizations. Since any form of combat sport involving grappling can be classified as wrestling, there continues to be multiple disciplines today that fall under the umbrella of wrestling. Aside from having grappling holds none of these disciplines have much in common with each other, and that includes the shape of physical location where competitors or sparring partners perform their moves. While Greco-Roman and Sumo wrestling is performed in a circular location, Chinese wrestling Shuai Jiao has no specific wrestling location structure to speak of. So even the term ‘wrestling ring’ is somewhat arbitrary and is not applicable to all wrestling disciplines that exist today.
Although history is sparse about the origin of professional wrestling as it is known today, once can trace it as far back as western 19 century carnivals where the kayfabe (staged) nature of the carnival athletic shows was kept as a closely guarded secret. When sometime in 1915 professional wrestling was revealed as a fake sport it led to massive decline in its popularity. Professional wrestling needed to reinvent itself in order to remain commercially viable, and figures like Ed Lewis and Joseph Mandow were just the men for this job. Lewis and Mondt brought about professional wrestling revival in 1920s by introducing the idea of signature taunts and popularizing heel tactics like distracting the referee. It is during this time period when professional wrestling came to realize that it needed to be more than just a variation of Greco-Roman wrestling; it needed to be bombastic.
Once again, the exact history of how the physical structure with the ropes and four sides came to be is unknown, but having this physical space greatly enhanced the sorts of moves that could be performed by professional wrestlers. The Greco-Roman wrestling aspect became but just one tool that was at a professional wrester’s disposal. At this point although professional wrestlers were still performing their moves in a wrestling ring, the physical shape of the ring was no longer a circle but a square. The term ‘squared circle’ is likely a pun born from adding ‘square’ to the ‘ring’ part of wrestling ring. But as noted before, even the term Wrestling Ring is not applicable to describing all variations of wrestling that exist today.