Search more than 275,000 synonyms, antonyms, related words, and idiomatic phrases. The thesaurus is more than just a list of synonyms; it is your guide to more precise and effective use of language.

thesaurus

noun

the·​sau·​rus thi-ˈsȯr-əs 

plural thesauri thi-ˈsȯr-ˌī 

-ˌē

or thesauruses thi-ˈsȯr-ə-səz 

1

a

: 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

2

: treasury, storehouse

thesaural

thi-ˈsȯr-əl 

adjective

Did you know?

In the early 19th century, archaeologists borrowed the Latin word thesaurus to denote an ancient treasury, such as that in 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 semantically related words organized into numerous categories. This work led to the common acceptance of the term thesaurus to refer to "a book of words and their synonyms." The word developed another meaning in the 1950s, when 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

Everything that Coltrane ever played was in that thesaurus. —David Marchese, Vulture, 4 Nov. 2024

Appropriate uses of generative AI include spell and grammar check or as a thesaurus. —Allie Volpe, Vox, 19 Sep. 2024

Make sure to fold the letter correctly and use the Jane Austen thesaurus to keep your language historical. —Annalise Frank, Axios, 12 July 2024

High Culture How to use a thesaurus to actually improve your writing Looking up big, fancy words won’t make your writing better. —Big Think, 24 June 2024

Word History

Etymology

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

First Known Use

circa 1823, in the meaning defined at sense 2

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Kids Definition

thesaurus

noun

the·​sau·​rus thi-ˈsȯr-əs 

plural thesauri -ˈsȯ(ə)r-ˌī 

-ˌē

or thesauruses -ˈsȯr-ə-səz 

: a book of words and their synonyms

Etymology

from scientific Latin thesaurus "treasury, storehouse, book of words," from Latin thesaurus "treasure, collection," from Greek thēsauros (same meaning) — related to treasure