thesaurus
Americannoun
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thesauruses,
plural
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thesauri
plural
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a dictionary of synonyms and antonyms, such as the online Thesaurus.com.
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any dictionary, encyclopedia, or other comprehensive reference book.
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a storehouse, repository, or treasury.
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Computers.
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an index to information stored in a computer, consisting of a comprehensive list of subjects concerning which information may be retrieved by using the proper key terms.
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a dictionary of synonyms and antonyms stored in memory for use in word processing.
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noun
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a book containing systematized lists of synonyms and related words
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a dictionary of selected words or topics
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rare a treasury
Usage
What is a thesaurus? A thesaurus is a book or program that lists synonyms and antonyms of words. A thesaurus can be a book you can find in a library, a website (such as Thesaurus.com), or a database stored in a word processor (such as the one you can find in Microsoft Word). The plural of thesaurus is thesauruses or thesauri. A synonym is a word that has the same meaning as another word. For example, huge, gigantic, massive, and large are synonyms of the word big. An antonym is a word that has the opposite meaning of another word. Small, tiny, and little are antonyms of the word big. Thesauri are useful when you want to avoid using the same word over and over or need a fancy word to describe something as being “not good” or “not fun.”
Other Word Forms
Noun Inflected Forms
Etymology
Origin of thesaurus
First recorded in 1730–40; from Latin thēsaurus, from Greek thēsaurós “treasure, treasury”
Explanation
A thesaurus is a reference book (or a really cool website, like the Visual Thesaurus) with an organized list of words and their synonyms. An Englishman named Peter Roget published the first modern English thesaurus in 1852. Roget had severe depression, and one of the ways he coped was to put his list-making and lexicographical (word analyzing) skills to use in a reference book that would group words, not alphabetically, but according to how similar their meanings were. This being the middle of the 19th century, there were no computers: Roget compiled and sorted all of his lists by hand.
Vocabulary lists containing thesaurus
TEKS ELAR Academic Vocabulary List (5th-7th grades)
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Language and Grammar - Introductory
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New Year, New Words: Vocabulary for January
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
He and other brainy classmates would be assigned an issue—like global warming—and compete to present the best possible solution, with only a dictionary and a thesaurus as their available tools.
From The Wall Street Journal ● Oct. 24, 2026
As the authors write, he turned to the thesaurus and made lists of traditional “pirating” words.
From Los Angeles Times ● Nov. 5, 2025
Ms Ain said that experts are also looking to create a legal thesaurus in Indian sign language that would help the deaf lawyers and litigants.
From BBC ● Oct. 8, 2023
Lithwick: Like, he should have had a thesaurus and defamed her using different words?
From Slate ● May 20, 2023
A massive thesaurus sits beside a dictionary that’s missing its hardcover spine.
From "Thirteen Reasons Why" by Jay Asher
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Why, at the moment the audience should be melting into tears over the death of this salesman, does the playwright introduce a word that sets viewers to thumbing their internal thesauri?
From Time Magazine Archive
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Nor do its plural forms, the highfalutin thesauri, or thesauruses, which sounds like a prehistoric creature.
From Time Magazine Archive
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Let's give thesauri to all songwriters incapable of dreaming up more original ways to voice that sentiment.
From Time Magazine Archive
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Ratings plummeted after the first episode, and critics dug out their thesauri to find new words for "awful."
From Time Magazine Archive
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There were then no short cuts of learning, no comprehensive lexicons, no dictionaries of antiquities, no carefully prepared thesauri of mythology and history.
From The Great Events by Famous Historians, Volume 07 by Rossiter Johnson
Stevens raised challenges in dozens of school districts over the Bible, dictionaries and thesauruses.
From Seattle Times ● Apr. 16, 2024
Amin said because some countries, particularly poorer ones may see phase-out as too restrictive, negotiators could even hit their thesauruses for alternatives to the much discussed phase-out or phase-down wording.
From Seattle Times ● Dec. 5, 2023
We all sat around a large table full of etymological dictionaries and thesauruses, and the children were discussing a line about being born in Mexico.
From New York Times ● Jun. 23, 2018
I encourage pupils to use dictionaries and thesauruses so pupils compile their own word banks.
From The Guardian ● Apr. 24, 2013
While other commentators, overwhelmed at the turn of events, had been forced to consult thesauruses in an effort to find synonyms for "wholesale repudiation" and "visceral disgust," Panetta had a slightly different take.
From Time Magazine Archive
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