The NCI Thesaurus and NCI Metathesaurus provide standard vocabularies for biomedical research. The content of the NCI Thesaurus is available for download in tab-delimited flat file format, Web Ontology Language (OWL) format and in LexGrid XML format. LexEVS is the terminology server used at NCI to support programmatic and web browser access to the vocabularies; it is also available for download and use by third parties.
NCI Thesaurus (NCIt) is NCI's reference terminology and core biomedical ontology, covering some 100,000 key biomedical concepts with a rich set of terms, codes, definitions, and relationships, including some 40,000 concepts used in FDA, CDISC, NCPDP, NIH and other coding standards.
NCI Metathesaurus (NCIm) provides a broad, concept-based mapping of terms from over 70 biomedical terminologies, whose 4,000,000 terms are mapped to 2,000,000 concepts representing their shared meanings.
LexEVS is the primary application programming interface to the EVS terminology server (LexBIG). This download provides access to the LexEVS source code, web services, java client.jar files, programming interfaces, documentation and more. LexEVS APIs provide access to vocabulary data and are based on the LexBIG service model. Access to the earlier releases of the EVS APIs is available for download from the EVS Archives page.