The Translation-Studies Dimension of Ontologising Terminological Definitions: Term Equivalence Under Concept-System Incommensurability

Drawing on verifiable textual material, the article establishes what the ontologisation of a terminological definition amounts to and what consequences it has for interlingual equivalence between English-language industrial resources and Ukrainian terminological codification. The material comprises four types of resources that codify the same subject field – oil-and-gas surface equipment – under four different regimes of definition-making: a formal ontology (the PCA PLM Reference Data Library, built on ISO 15926-14 / Industrial Data Ontology), a standardised data dictionary (CFIHOS v2.0), a professional glossary (the SLB Energy Glossary), and Ukrainian national terminological standards (ДСТУ 3809-98, ДСТУ 3063-95, ДСТУ 2611-94). A core sample of twenty concepts was coded against nine parameters: definition type, genus, explicit top-level categories, life-cycle markers, mode of fixing relations, functional component, inter-version shift, type of interlingual equivalence, and source of equivalence. It was established that, on definition pairs with shared wording, ontologisation reduces to a substitution in the genus slot while the differentia remains invariant, and that the operation is graded: from zero intervention through a bare category swap to full substitution with a functional genus. Life-cycle markers were shown to be removed at the very first step of standardisation and inherited thereafter in de-temporalised form, while the coverage of a resource was shown to follow its purpose rather than its subject field. A typology of equivalence asymmetries was substantiated: the chain of equivalence declared by the resources themselves closes at the level of the term and breaks at the level of the concept. The initial hypothesis was refined: ontological commitments define the boundaries of the possible definitional space, while the filling of that space remains with the compiler. Prospects are outlined: an audit of definitional quality in machine-readable terminological resources, a diachronic study of inter-version definitional shift, and a full typology of translation asymmetries