Generally a completely unambiguous, declarative, formal, highly restricted language
There are a multitude of ontology languages. Each of them seeks to remove ambiguity and perfectly encapsulate clear information and knowledge.
Examples
- Common Logic
- Knowledge Interchange Format (KIF)
- Web Ontology Language (OWL)
- Resource Description Framework (RDF)
- Its equivalents, like JSON-LD
- OntoUML (an extension of UML)
- IDEF5 (see: IDEF)
- Object-Process Methodology (see: OPM)
- Attempto Controlled English