# Ontology | Definition

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*“In AI, an **ontology** is a specification of the meanings of the symbols in an information system. That is, it is a specification of a conceptualization…\[it] often involves a **community** to agree on the meanings of symbols….*

*… an ontology consists of a vocabulary of the categories of the things (both classes and properties) that a **knowledge base** may want to represent; ….an organization of the categories...; and a set of axioms restricting the meanings of some of the symbols to better reflect their meaning… ultimately, the relationships are grounded out into **primitive**...”*

*Artificial Intelligence: foundations of computational agents, Cambridge University Press, 2017, Sec. 13.3. the 2nd Edition*