A thesaurus is a controlled vocabulary arranged in a known order and structured so that equivalence, homographic, hierarchical, and associative relationships among terms are displayed clearly and identified by standardized relationship indicators that are

A thesaurus is a controlled vocabulary arranged in a known order and structured so that equivalence, homographic, hierarchical, and associative relationships among terms are displayed clearly and identified by standardized relationship indicators that are employed reciprocally. The primary purposes of a thesaurus are (a) to facilitate retrieval of documents and (b) to achieve consistency in the indexing of written or otherwise recorded documents and other items, mainly for postcoordinate information storage and retrieval systems.