In the computer science sense. Except that it wouldn't be surprising if I were dealing with natural language or any other obvious set of references to the world of messy human concepts. But it's not anything like that; this has managed to come up entirely within a domain of what ought to be well defined and technically precise concepts, and in the course of trying to get what seemed like perfectly sensible things done it has turned out that there's an underlying problem that inadequate effort has been given to precisely defining a domain-specific ontology.