Public-private partnership (PPP) is a strategically important management tool that allows the state and the private sector to jointly implement projects in various fields, such as infrastructure, health care, education, and others, to promote economic development. However, the successful implementation of PPP requires a clear understanding of the basic definitions and concepts underlying it. This research work is devoted to working out the content of basic definitions in the context of the establishment and development of PPPs. It examines the main terms, such as "public-private partnership", "public-private partnership", "infrastructure projects" and others, including their definition, essence and role in the formation of an effective model of cooperation between the state and the private sector. The conducted research is based on the analysis of scientific literature, legal acts and practical experience of PPP implementation in different countries of the world. It is aimed at revealing the essence and meaning of each of the definitions, highlighting the key aspects that affect their interpretation and use in practice. In addition, the work draws attention to the evolution of concepts and terms in the context of the establishment and development of PPPs over time. Taking into account the dynamics of the global market and changing economic conditions, the work analyzes the impact of new factors on the understanding and use of basic definitions in PPP practice.The main results of the study provide a clear and concrete understanding of the basic definitions of PPPs, which will contribute to improving the quality of planning, implementation and management of PPP projects. In addition, they can become the basis for further research in this area, including the development of new theoretical models and methods for assessing the effectiveness of PPPs.All this indicates the relevance of the topic and the importance of further research in order to improve PPP practice and promote sustainable economic development .