Thesaurus

Synonym dictionaries have a long history. The word 'thesaurus' was used in 1852 by Peter Mark Roget for his ''Roget's Thesaurus''.
While some works called "thesauri", such as ''Roget's Thesaurus'', group words in a hierarchical hypernymic taxonomy of concepts, others are organised alphabetically or in some other way.
Most thesauri do not include definitions, but many dictionaries include listings of synonyms.
Some thesauri and dictionary synonym notes characterise the distinctions between similar words, with notes on their "connotations and varying shades of meaning". Some synonym dictionaries are primarily concerned with differentiating synonyms by meaning and usage. Usage manuals such as Fowler's ''Dictionary of Modern English Usage'' or ''Garner's Modern English Usage'' often prescribe appropriate usage of synonyms.
Writers sometimes use thesauri to avoid repetition of words – elegant variation – which is often criticised by usage manuals: "Writers sometimes use them not just to vary their vocabularies but to dress them up too much". Provided by Wikipedia
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