Thesaurus
A controlled vocabulary that defines preferred terms and maps their relationships (broader, narrower, related, and synonyms) so records and information are described and retrieved consistently.
A thesaurus is a controlled vocabulary that does more than list approved terms: it structures the relationships among them. For each preferred term it identifies broader terms, narrower terms, related terms, and non-preferred synonyms (use/used-for references) that steer searchers toward the right heading. The aim is consistency — different people describing the same subject land on the same term, and someone retrieving records finds everything filed under it regardless of the words they first tried.
In recordkeeping, a thesaurus underpins reliable classification, subject indexing, and metadata tagging, which in turn support findability, defensible retention, and discovery during litigation or access requests. It is more relationship-rich than a flat taxonomy: a taxonomy arranges categories hierarchically, while a thesaurus also captures associative and equivalence links. For example, a records program might make “Procurement” the preferred term, mark “Purchasing” as a synonym to use it, and relate it to “Contracts.” Because controlled vocabularies travel with records as metadata, a well-maintained thesaurus pays off across system migrations and long-term electronic preservation.