Thesaurus

A thesaurus is a reference work that lists words grouped together according to similarity of meaning (containing synonyms and sometimes antonyms), in contrast to a dictionary, which contains definitions and pronunciations. The largest thesaurus in the world is the Historical Thesaurus of the Oxford English Dictionary, which contains more than 920,000 entries.

Read more about Thesaurus:  History, Thesauruses in IT, Literary Thesauruses, Specialized Thesauruses For Information Retrieval, Thesauruses's Formats, Standards and Manuals