Dairen is a term often used in modern language as a synonym for a circle or a roundabout. However, there are numerous other words that can be used to describe a circular shape or formation. These words include round, sphere, globe, ring, loop, wheel, disk, ball, and orb. Each of these words carries a slightly different connotation and can be used to describe a range of circular objects or concepts, from celestial bodies to architectural features. Ultimately, the choice of synonym will depend on the context and desired effect in a given piece of writing or conversation.