But a definition is a dynamic process. Real definitions, nominal definitions, prescriptive, contextual, recursive, inductive, persuasive, impredicative, extensional and intensional definitions, are stars in a galaxy of alternative modes of explanation. People are trying to define life or love by resorting to chemical reactions. This reductionism inevitably and invariably leads to the Locke paradoxes. It is true that a definition must include all the necessary conditions to the definiendum.
Chemical reactions are a necessary condition to life.
But they are not sufficient conditions. A definition must include all the sufficient conditions as well. A statement which captures the meaning, the use, the function and the essence of a term or a concept.