In Semantic Web usage, Vocabulary is a near-synonym for Ontology though "trend is to use the word ontology for more complex, and possibly quite formal collection of terms, whereas vocabulary is used when such strict formalism is not necessarily used or only in a very loose sense." Whatever else they might be called, DCMI Metadata Terms, the AGROVOC concept scheme, and the Bibliographic Ontology (BIBO) are also vocabularies.