The UMLS Semantic Network is one of three UMLS Knowledge Sources developed as part of the Unified Medical Language System project. The network provides a consistent categorization of all concepts represented in the UMLS Metathesaurus.
The UMLS Semantic Network is available in unit record and relational format and is distributed subject to these terms and conditions.
The UMLS semantic network reduces the complexity of the Metathesaurus by grouping concepts according to the semantic types that have been assigned to them. For certain purposes, however, an even smaller and coarser-grained set of semantic type groupings may be desirable. The UMLS semantic groups have been established for this purpose.
Further information about the UMLS Semantic Network can be found at:
McCray AT. An upper level ontology for the biomedical domain. Comp Funct Genom 2003; 4:80-4.