What Is an "Ontology"?
An ontology is a controlled vocabulary of well-defined terms with specified relationships between them capable of interpretation by both humans and computers. This systematized knowledge facilitates data sharing between experiments and data sources thus encouraging cooperative usage of data produced in this new information age.
To learn more about what biomedical ontologies are and how they are used, view RGD's Introduction to Biomedical Ontologies Video series.
You can also explore a number of ontologies and learn more about their use in the biomedical sciences at the National Center for Biomedical Ontologies.