thesaurus

American  

[thi-sawr-uhs] / θɪˈsɔr əs /

noun

plural

thesauruses, thesauri

1. a dictionary of synonyms and antonyms, such as the online Thesaurus.com.

2. any dictionary, encyclopedia, or other comprehensive reference book.

3. a storehouse, repository, or treasury.

4. Computers.

   1. 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.

   2. a dictionary of synonyms and antonyms stored in memory for use in word processing.

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thesaurus British  

/ θɪˈsɔːrəs /

noun

1. a book containing systematized lists of synonyms and related words

2. a dictionary of selected words or topics

3. rare a treasury

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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.”

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.

Example Sentences

She undoubtedly has a thesaurus earmarked and highlighted like a high school student’s SparkNotes copy of “Macbeth.”

From Salon • Jan. 7, 2025

And now you can break out the thesaurus.

From Los Angeles Times • Mar. 20, 2024

At their simplest, these programs mask plagiarism through liberal use of a thesaurus; replace enough words with synonyms and hopefully nobody will ever find the original source.

From Scientific American • Sep. 28, 2023

Lithwick: Like, he should have had a thesaurus and defamed her using different words?

From Slate • May 20, 2023

She’s some sort of mechanized humanoid, made up of spare computer parts, all the leafy green vegetables that no one ever eats and thesaurus pages.

From "Liar, Liar" by Gary Paulsen

Related Words

• reference book