In this paper, a terminological framework, both theoretical and methodological, backed by empirical data, is proposed in order to highlight the particular questions to which attention should be paid when conceiving an evaluation scheme for definition extraction (DE) in terminology. The premise is that not just any information is relevant to defining a given concept in a given expert domain. Therefore, evaluation guidelines applicable to DE should integrate some understanding of what is relevant for terminographic definitions and in which cases. This, in turn, requires some understanding of the mechanisms of feature selection. An explanatory hypothesis of feature relevance is then put forward and one of its aspects examined, to see to what extent the example considered may serve as a relevance referential. To conclude, a few methodological proposals for automating the application of relevance tests are discussed. The overall objective is to explore ways of empirically testing broader theoretical hypotheses and principles that should orient the conception of general guidelines to evaluate DE for terminographic purposes.