the·​sau·​rus | \ thi-ˈsȯr-əs How to pronounce thesaurus (audio) \
plural thesauri\ thi-​ˈsȯr-​ˌī How to pronounce thesauri (audio) , -​ˌē \ or thesauruses\ thi-​ˈsȯr-​ə-​səz How to pronounce thesauruses (audio) \

Definition of thesaurus

1a : a book of words or of information about a particular field or set of concepts especially : a book of words and their synonyms
b : a list of subject headings or descriptors usually with a cross-reference system for use in the organization of a collection of documents for reference and retrieval

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Other Words from thesaurus

thesaural \ thi-​ˈsȯr-​əl How to pronounce thesaural (audio) \ adjective

Did You Know?

In the early 19th century, archaeologists borrowed the Latin word thesaurus to denote an ancient treasury, such as that of a temple. Soon after, the word was metaphorically applied to a book containing a "treasury" of words or information about a particular field. In 1852, the English scholar Peter Mark Roget published his Thesaurus of English Words and Phrases, in which he listed a treasury of related words organized into numerous categories. This work led to the common acceptance of the term "thesaurus" for "a book of words and their synonyms." Finally, during the 1950s, "thesaurus" began being used in the field of word processing to refer to a list of related terms used for indexing and retrieval.

Examples of thesaurus in a Sentence

Recent Examples on the Web My rudimentary word processing program had a thesaurus. Alexandra Lange, Curbed, "Let Christopher Alexander design your life," 11 July 2019 But he is adored by the party members in the country who cherish his Bertie Wooster-with-a-thesaurus speeches and flamboyant style. The Economist, "And then there were two," 20 June 2019 Pack a low-back chair and a picnic (and maybe a thesaurus), and skip merrily off into the forest with Theseus and Hippolyta. Brittany Martin, Los Angeles Magazine, "The 7 Best Things to Do in L.A. This Weekend," 27 June 2018 Be your own thesaurus and fact-checker, and squint with your ears at phrasing that comes off as aggressively neutral. Michael Andor Brodeur,, "The official language of the US? It’s euphemism.," 21 June 2018 Regular viewers of White House press briefings are familiar with Newsmax's John Gizzi, a human thesaurus with a deep voice and deliberate style of questioning that stands out in a frenzied room. Callum Borchers, Washington Post, "Would Bill O’Reilly’s viewers follow him to a smaller network?," 16 May 2018 The physicians who inspected the twins included Dr. Peter Mark Roget, compiler of his eponymous thesaurus. Vanessa Hua, San Francisco Chronicle, "‘Inseparable,’ by Yunte Huang," 10 May 2018 From ThinkProgress: The first five vendors combined offered just five romance novels, 14 religious texts, 24 drawing or coloring books, 21 puzzle books, 11 how-to books, one dictionary and one thesaurus. Monique Judge, The Root, "New York Department of Corrections Puts Severe Restrictions on Books Prisoners Can Receive," 8 Jan. 2018 No thesaurus on earth can provide the appropriate adjectives. Matt Calkins, The Seattle Times, "At least none of the Seahawks tried to hide the fact of just how awful they played Sunday," 17 Dec. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'thesaurus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of thesaurus

circa 1823, in the meaning defined at sense 2

History and Etymology for thesaurus

New Latin, from Latin, treasure, collection, from Greek thēsauros

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Time Traveler for thesaurus

Time Traveler

The first known use of thesaurus was circa 1823

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Cite this Entry

“Thesaurus.” The Dictionary, Merriam-Webster Inc., Accessed 7 December 2019.

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How to pronounce thesaurus (audio)

English Language Learners Definition of thesaurus

: a book in which words that have the same or similar meanings are grouped together


the·​sau·​rus | \ thi-ˈsȯr-əs How to pronounce thesaurus (audio) \
plural thesauri\ -​ˈsȯr-​ˌī , -​ˌē \ or thesauruses\ -​ˈsȯr-​ə-​səz \

Kids Definition of thesaurus

: a book of words and their synonyms

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