[ thi-sawr-uhs ]
See synonyms for thesaurus on
noun,plural the·sau·rus·es, the·sau·ri [-sawr-ahy]. /-ˈsɔr aɪ/.
  1. a dictionary of synonyms and antonyms, such as the online

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

  1. a storehouse, repository, or treasury.

  2. Computers.

    • 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.

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

Origin of thesaurus

First recorded in 1730–40; from Latin thēsaurus, from Greek thēsaurós “treasure, treasury”

Words Nearby thesaurus Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use thesaurus in a sentence

British Dictionary definitions for thesaurus


/ (θɪˈsɔːrəs) /

nounplural -ruses or -ri (-raɪ)
  1. a book containing systematized lists of synonyms and related words

  2. a dictionary of selected words or topics

  1. rare a treasury

Origin of thesaurus

C18: from Latin, Greek: treasure

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012