OWL
Web Ontology Language (OWL) zone
From https://en.wikipedia.org/wiki/Web_Ontology_Language:
The Web Ontology Language (OWL) is a family of knowledge representation languages for authoring ontologies. Ontologies are a formal way to describe taxonomies and classification networks, essentially defining the structure of knowledge for various domains: the nouns representing classes of objects and the verbs representing relations between the objects.