NucLexNuclear Medicine Lexicon and Theranostics Ontology
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Lexicon · The human story of meaning

Lexicon entryDraftNX-C003

Taxonomy

Fully specified name: Taxonomy (concept)

A classification organized according to stated criteria, often as a hierarchy.

Scope note
The organizing criterion must be explicit.
Synonyms
None recorded as true synonyms in this context.
Monograph
Taxonomy (planned; brief only)
External mappings
None recorded. In W0 no mapping to SNOMED CT® or any external authority is asserted for this entry. A future mapping record will carry source system, identifier, version, relation type, evidence, author, confidence where meaningful, and review state.
Formal status
Editorial entry only. It is not part of any released ontology and a prose edit here changes no formal definition.

Draft. This entry is an unreviewed draft. Its sources have not been checked by a named person and no domain reviewer has approved it. Treat every claim as provisional.

Notes

A taxonomy arranges things into classes and subclasses by a stated criterion. The criterion is the whole point: radiopharmaceuticals can be classified by radionuclide, by emission type, by targeting mechanism, by clinical use, or by regulatory status, and each criterion yields a different tree. A taxonomy that does not state its criterion cannot be checked, and two taxonomies built on different criteria cannot be merged by placing one under the other.

In biology the word carries the weight of Linnaean classification of organisms. In information management it is used more loosely for any hierarchical arrangement of terms, which is where confusion with Ontology begins. A taxonomy expresses one relationship, usually "is a kind of," and expresses it along one axis. An ontology may contain a taxonomy as its backbone but adds other relationship types and may state axioms about them. A parent in a taxonomy is a classification, not an explanation: that an agent is classed as a beta emitter says nothing about why it localizes where it does. The monograph works through a synthetic radiopharmaceutical classification to show the difference.