...a possible confusion arises between an ontology intended as a particular conceptual framework at the semantic level (interpretations 2-3) and an ontology intended as a concrete artifact at the syntactic level, to be used for a given purpose (interpretations 4-7). This is an important distinction, and it is evident that we cannot use the same technical term to denote both things.

We shall use the term conceptualization to denote a semantic structure which reflects a particular conceptual system (interpretation 3 in Fig. 1), and ontological theory to denote a logical theory intended to express ontological knowledge (interpretation 5). The underlying intuition is that ontological theories are designed artifacts, knowledge bases of a special kind which can be read, sold or physically shared. Conceptualizations, on the other hand, are the semantical counterpart of ontological theories. The same ontological theory may commit to different conceptualizations, as well as the same conceptualization may underlie different ontological theories. The term “ontology” will be used ambiguously, either as synonym of “ontological theory” or as synonym of “conceptualization”. We need only to be consistent to the choice made within the same statement.

[...] 1. Ontological engineering is a branch of knowledge engineering which uses Ontology to build ontologies. 2. Ontologies are special kinds of knowledge bases. 3. Any ontology has its underlying conceptualization. 4. The same conceptualization may underlie different ontologies. 5. Two different knowledge bases may commit to the same ontology.