Thesaurus of English Words and Phrases (faux leather binding)

A thesaurus is a reference work which arranges words by their meanings (or in simpler terms, a book where one can find different words with similar meanings to other words), sometimes as a hierarchy of broader and narrower terms, sometimes simply as lists of synonyms and antonyms. They are often used by writers to help find the best word to express an idea:

...to find the word, or words, by which [an] idea may be most fitly and aptly expressed

Peter Mark Roget, 1852