Functions of a Thesaurus
The major functions of a thesaurus include the following :
a) it provides a standard vocabulary for a given subject field by exercising control on the vocabulary of terms used in an indexing language. Methods of controlling the vocabulary are:
- out of all possible synonyms and quasi-synonyms, only one term is selected as a descriptor,
- the scope of the meaning of the term is clearly indicated in a scope note for the best suitability of the selected meaning,
- a definite rule is followed for compound terms, word-forms, number (singular/plural) and spellings are standardized, and
- homonyms are differentiated by qualifiers;
b) it shows the intrinsic, semantic relationship existing between, terms, and thus provides system of references between terms;
c) it helps the indexer and the searcher in the choice of preferred terms;
d) it provides hierarchical display of terms so that a search can be broadened or narrowed systematically;
e) it increases the speed of retrieval by use of indexing terms and search terms; and
f) it provides a map of a 'given subject field, which helps to understand the structure of the field.