Scientific concepts are theories about phenomena, so their definitions shift with new knowledge.

Evidence

In contrast, this volumes argues that a concept involves a theoret­ ical and empirical analysis of the object or phenomenon referred to by the word. A good concept draws distinctions that are important in the behavior of the object. The central attributes that a definition refers to are those that prove relevant for hypotheses, explanations, and causal mechanisms. In a theoretical and empirical view of sci­ entific concepts their semantics change as our understanding of the phenomenon changes. — Gary Goertz, Social Science Concepts, 28

Categorization

• DEFINE: Stakes out a theoretical-empirical account of ‘concept’ against purely semantic or stipulative definitions.
• XREF: Echoes the semantics-vs-ontology debates in the philosophy-of-language material on reference and conceptual change.