A circular can refer to different things depending on the context. Here are some possible meanings:

• Circular definition: A circular definition is a type of definition that uses the term(s) being defined as part of the description or assumes that the term(s) being described are already known. There are several kinds of circular definition, and several ways of characterizing the term: pragmatic, lexicographic, and linguistic.

• Circular: A circular can also refer to an official letter or advertisement that is sent to a large number of people at the same time.

• Circular shape: A circular shape is a shape that is round, like a circle. It can be used to describe objects that are circular in shape, such as a circular driveway or a circular flowerbed.

• Circular economy: A circular economy is a system where materials never become waste and nature is regenerated. In a circular economy, products and materials are kept in circulation through processes like maintenance, reuse, refurbishment, remanufacture, recycling, and composting. The circular economy tackles climate change and other global challenges, like biodiversity loss, waste, and pollution, by decoupling economic activity from the consumption of finite resources.

Its important to note that the meaning of "circular" can vary depending on the context, so its always best to consider the context in which the term is being used.