Environmental, as well as economic and social/cultural aspects of sustainability, are important when striving for sustainable production and consumption of food and meals. However, a terminology including specific concepts within the combined area of food, meals and sustainability is lacking. In order to investigate how food, meals and sustainability can be conceptualized together, the aim of this paper is to explore the compound concept of circular gastronomy to discover how it can be understood and applied, and its potential opportunities and challenges. A further aim is to provide a definition of circular gastronomy. The data collection was conducted in two phases of an explorative sequential mixed-method study comprising qualitative focus groups followed by a web-based survey. The results revealed the complexity in the compound concept of circular gastronomy, both in what might be included and in how it could be understood and applied. Circular gastronomy was considered to be useful, interesting and trendy; however, understanding circularity and gastronomy as a compound concept was also found to be challenging. As a result of the study, and previous understandings of circular and gastronomy, a definition of circular gastronomy is provided. Developing the understanding of circular gastronomy is an attempt to contribute to the conceptual development of the combined area of food, meals and sustainability.