Lexicographic and logical definitions for terms

Definitions are a central concept in terminology. The original idea of definition stems from logic. Logical definitions are based on a set of necessary and sufficient conditions which determine a precise borderline of a concept. However, natural meanings are prototype-based, so that they do not have natural borderlines. In dictionaries, we find definitions that characterize the prototype. Therefore, they are generally not adequate as logical definitions. In terminology, this creates a tension. Dictionaries cannot be seen as a description of the vocabulary of a language, but should be interpreted as a source of information about the use of words. Logical definitions only have a role when they are supported by an authority. In domains in which rules have to be enforced, terms that determine the interpretation of a rule should have a logical definition supported by the domain-specific authority. In domains relating to empirical science, terms that are used in the evaluation of theories and theoretical claims should also have logical definitions. To what extent a generally accepted logical definition is achievable in such domains depends on the existence of a body that is generally accepted as the authority in the relevant domain.