[ thi-sawr-uhs ]
/ 胃瑟藞s蓴r 蓹s /
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noun, plural the路sau路rus路es, the路sau路ri [-sawr-ahy]. /-藞s蓴r a瑟/.
a dictionary of synonyms and antonyms, such as the online Thesaurus.com.
any dictionary, encyclopedia, or other comprehensive reference book.
a storehouse, repository, or treasury.
  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.
Test how much you really know about regular and irregular plural nouns with this quiz.
Question 1 of 9
Which of the following nouns has an irregular plural form?

Origin of thesaurus

First recorded in 1730鈥40; from Latin th膿saurus, from Greek th膿saur贸s 鈥渢reasure, treasury鈥
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, 漏 Random House, Inc. 2022


What is a聽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 鈥渘ot good鈥 or 鈥渘ot fun.鈥

Why is聽thesaurus important?

The first records of the term thesaurus come from around 1730. It ultimately comes from the Greek th膿saur贸s, meaning 鈥渢reasure鈥 or 鈥渢reasury.鈥 While the word thesaurus can mean a 鈥渢reasury鈥 or 鈥渟torehouse,鈥 this usage is very rare. Instead, thesaurus almost always refers to books, websites, or programs that are treasuries of synonyms and antonyms.

Repeatedly using the same word over and over is likely to bore or disinterest a reader. Even experienced authors like to keep a thesaurus handy to spice up their writing and possibly learn some new interesting words. Luckily, a fantastic thesaurus is readily available for anyone to use at Thesaurus.com.

Did you know ... ?

British doctor Peter Mark Roget (1779鈥1869) is credited as being the writer of the first modern thesaurus. Roget鈥檚 Thesaurus is still updated and published today, and National Thesaurus Day is held on January 18, Roget鈥檚 birthday.

What are real-life examples of聽thesaurus?

You can usually find a thesaurus like the one pictured below in your local library or bookstore. Alternatively, you can visit Thesaurus.com for all of your synonym-finding needs!

Most people know that a thesaurus is the tool to use if you need to find synonyms.


What other words are related to聽thesaurus?

Quiz yourself!

True or False?

A thesaurus lists homonyms and pseudonyms of words.

How to use thesaurus in a sentence

British Dictionary definitions for thesaurus

/ (胃瑟藞s蓴藧r蓹s) /

noun plural -ruses or -ri (-ra瑟)
a book containing systematized lists of synonyms and related words
a dictionary of selected words or topics
rare a treasury

Word Origin for thesaurus

C18: from Latin, Greek: treasure
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition 漏 William Collins Sons & Co. Ltd. 1979, 1986 漏 HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012