The term 'Circular Theater' refers to a type of theater that is shaped like a circle or oval. It is also known as an ARENA theater, which is the crossword solution for the term. ARENA theaters are typically used for performances that require a large amount of space, such as musicals, operas, and plays. They are also often used for sporting events, concerts, and other large gatherings. The circular shape of the theater allows for a more intimate atmosphere and better acoustics.