When it comes to deriving ontology terms from the natural language definitions provided in expert compendia, such as the Gold Book, one needs to be aware of the fact that these will always differ to some degree. While the natural language definitions in compendia are intended to be understood within the general context of reality, the natural language definitions provided for ontology terms are meant to be understood within the context of the specific chosen ontological framework. This framework includes the subsumption hierarchy, axiomatization, and scope of the ontology, which all reflect a particular ontological commitment. In other words, the main concepts and relations used in ontological textual definitions should at best also be defined in the ontology itself, so that they can be translated into logical axioms. The implication is that Gold Book term definitions may not simply be translated losslessly into formal ontology term definitions. When we speak of using Gold Book definitions as a canonical source of chemical domain knowledge to support the ontology developer on how to properly define chemical ontology terms, one should thus not think of this process as a kind of translation or adaptation, but rather as a mapping of meaning from one format to a narrower semantic format.