The idea underlying biomedical ontology is that, if common terms are used to annotate or tag heterogeneous data collected by scientists working in different disciplines, then these data will be more easily reused for integration and
analysis. To this end, the terms in ontologies need to be carefully defined. Smith examines definitions
of terms central to ageing research in this light, focusing on the Gene Ontology (GO), the Foundational Model of Anatomy Ontology (FMA) and the Plant Ontology (PO).