A specification of a conceptualization.
"In the context of knowledge sharing, I use the term ontology to mean a specification of a conceptualization. That is, an ontology is a description (like a formal specification of a program) of the concepts and relationships that can exist for an agent or a community of agents. This definition is consistent with the usage of ontology as set-of-concept-definitions, but more general. And it is certainly a different sense of the word than its use in philosophy."
From Gruber, T. "What is an Ontology?" http://www-ksl.stanford.edu/kst/what-is-an-ontology.html.
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