UMLS Metathesaurus Finely Granular Concepts
Concepts, terms, and attributes from many controlled vocabularies
New inter-source relationships, definitional information, use information
Scope determined by combined scope of source vocabularies
Strict definition of synonymy
Notes:
With this many strings and terms, we chose to make a strict definition of synonymy. Unlike thesauri, we do not use any entry terms. And things are considered synonymous only if they are essentially identical. As a result, fine distinctions in naming(e.g., carcinoma of the prostate and adenocarcinoma of the prostate) are preserved as different concepts.
With this finely granular conceptual structure, it is necessary to organize material in such a way that things with similar, but not identical, meanings are coneptually related to one another. The ways in which this occurs has been called “semantic locality”, and we often refer to the “semantic neighborhood” of a concept.
In order to insure this semantic locality is rich in information, we represent the relationships betweeen concepts asserted by each of the sources, review the important relationship, and add definitional and other information to the concepts where it is possible.
But, and here is an important caveat, we do not (in general) ADD any new concepts not in one of the source vocabularies that we use. Our scope is limited to what is in the source vocabularies.