In cases where an ontology developer needs to use a different wording when mapping the meaning of a Gold Book definition into a given ontological context, we advise using the standard semantic web predicate from the ontology PROV-O called hadPrimarySource, to indicate clearly that the Gold Book served as the primary source for the soundness of the ontological definition. This approach may be particularly useful if the IUPAC Gold Book definition text is too extensive, or the scope and formal framework of the ontology calls for it.