n. (pl., thesauruses, thesauri)
alist of words with related meanings, including synonyms and antonyms
aspecialized vocabulary of words and phrases, commonly used for indexing, that indicates a preferred term among synonyms and shows relationships between terms
A thesaurus is distinguished from dictionaries and glossaries, the latter not establishing a preferred term among synonymous terms. A thesaurus often contains nothing more than headings and their relationships, where dictionaries and glossaries usually contain definitions and annotations on word use.
ANSI/NISO Z39.19-2005, 9A controlled vocabulary arranged in a known order and structured so that the various relationships among terms are displayed clearly and identified by standardized relationship indicators. Relationship indicators should be employed reciprocally.