Emtree

Emtree is a controlled vocabulary and ontology used to index and retrieve life sciences literature. It is developed and maintained by Elsevier and serves as the indexing backbone for the Embase database, a major biomedical literature resource used by researchers, clinicians, and professionals.

Emtree provides a hierarchical structure of concepts, each associated with a preferred term, numerous synonyms, and often acronyms. The terms are organized into broad categories such as drugs and chemicals, diseases, procedures, anatomy, microbiology, pharmacology, and toxicology, among others. Each concept is assigned a unique identifier and linked to related terms through relationships such as broader, narrower, and related terms, enabling both precise tagging and semantic search.

Key features of Emtree include multilingual terms, standardized spelling variants, and extensive coverage of pharmacology, toxicology, clinical medicine, and experimental sciences. The vocabulary supports indexing consistency across Embase records and facilitates search refinement, query expansion with synonyms, and topic filtering. It also enables interoperability through mappings to other vocabularies and taxonomies, aiding researchers who work with multiple databases.

Emtree is proprietary to Elsevier and is updated regularly to reflect new terminology, emerging drugs, diseases, and procedures, as well as changes in clinical practice and scientific nomenclature. Access to Emtree terms is primarily through Elsevier’s products, such as Embase, and through accompanying documentation and indexing guidelines for librarians and information specialists.

See also: Embase, MeSH, SNOMED CT.