The ideology of economic growth focused on overproduction and overconsumption demonstrates its backwardness and inconsistency in today's world, where there is an acute shortage of raw materials and energy resources and an increase in human waste, which generally aggravates the environmental situation. To solve this problem, the concept of a circular economy or, as it is also called, a closed cycle economy can be a very effective tool. It includes recycling and reuse of production wastes, replacement of materials, introduction of more durable components of materials, use of renewable resources. However, one of the most important scientific problems is the insufficient study of the theoretical and methodological foundations that form the conceptual and categorical apparatus of the concept under study. This article describes approaches to the study of closed cycle economics, as well as the concept of circular economics in the works of domestic and foreign authors. This article describes the approaches to the study of the circular economy, as well as the concept of circular economy in the works of domestic and foreign authors. As a result of the synthesis of scientists' concepts on the definitions formulated for the designated terms, the authors determine that the circular economy in the scientific community is currently understood as a way to solve environmental problems; a new trend as the basis for the industrial revolution; strategy; sustainable development initiative; circular economy; type of economic activity; strategy; philosophy; economic model. The authors reasonably conclude that the most complete definitions of circular economy are those in which it is understood as a closed economic system for the exchange of resources.