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 Grab your thesaurus and look up another word for bad, another word for tragic. Gregg Doyel, Indianapolis Star, "Doyel: The coronavirus has taken a lot from us — but not Hoosier Hospitality," 13 Apr. 2020 Flip through a thesaurus or take online quizzes to test your vocabulary, and gradually intumesce your personal lexicon and chevvy your kin with your verbosity. Scottie Andrew, CNN, "Social distancing doesn't have to doom your weekends. We have ideas," 14 Mar. 2020 Like a thesaurus or maybe War and Peace (sorry, Tolstoy). - Open the cover and first few pages and secure the remaining pages with clamps. Popular Mechanics Editors, Popular Mechanics, "How To Make a Book Safe," 22 Feb. 2020 The event prompted a thesaurus’s load of invective. Clifton Leaf, Fortune, "The case for a national primary," 11 Feb. 2020 The various returns to (or re-volcanic-eruptions of) figurative image-making in current art make Saul’s multifarious tropes a handy visual thesaurus for engaging the mind through corporeal mimesis. Peter Schjeldahl, The New Yorker, "The In-Your-Face Paintings of Peter Saul," 10 Feb. 2020 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

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.” Dictionary, Merriam-Webster, Accessed 26 Sep. 2020.

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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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