A formal representation that defines a set of concepts within a domain is known as what?

The concept being described in the question is an ontology. An ontology serves as a structured framework that defines a set of concepts and the relationships between them within a particular domain. This formal representation allows for better communication and understanding among stakeholders in that domain by providing a shared vocabulary and a clear understanding of how different concepts relate to one another.

In various fields, ontologies play a critical role in organizing knowledge, facilitating data exchange, and improving the interoperability of systems. By capturing both the definitions of concepts and their interrelations, ontologies enable more sophisticated queries and analyses, which is vital in areas like health information management, where complex data relationships exist.

In contrast to other options like hierarchy, nomenclature, and terminology, which may focus on classification, naming, or specific terms within a domain, ontology encompasses a more comprehensive structure that includes both concepts and their interconnections. This makes it paramount for modeling knowledge in various disciplines effectively.