Thesaurus: History, Definition, and Examples

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A thesaurus is a book of synonyms, often including related words and antonyms. Plural is thesauri or thesauruses.

Peter Mark Roget (1779-1869) was a physician, a scientist, an inventor, and a Fellow of the Royal Society. His fame rests on a book that he published in 1852: Thesaurus of English Words and Phrases. Neither Roget nor thesaurus is copyrighted, and several different versions of Roget's work are available today.

Etymology: From the Latin, "treasury."

Pronunciation: thi-SOR-us

Observations

John McPhee: The value of a thesaurus is not to make a writer seem to have a vast vocabulary of recondite words. The value of a thesaurus is in the assistance it can give you in finding the best possible word for the mission that the word is supposed to fulfill.

Sarah L. Courteau: A thesaurus can extract that word that's on the tip of your tongue but can't quite reach your lips. It reacquaints you with words you've forgotten and presents ones you don't know. It suggests relationships but usually doesn't spell them out—like a hostess who invites you to a party of well-connected guests where you're expected to circulate and make your own introductions. In our hyper-searchable world, in which shelf browsing and even book skimming are on the wane, the thesaurus reminds us that precision isn't always a matter of predestined calibration. It can still be an informed choice.

T. S. Kane: The limitations of most thesauri are revealed in the directions given in one edition of Roget:

Turning to No. 866 (the sense required) we read through the varied list of synonyms... and select the most appropriate expression. [Italics added]

The matter of selection is critical, and a thesaurus does not offer much help with that. For example, among the synonyms listed in one Roget under the category seclusion/exclusion are solitude, isolation, loneliness, and aloofness. They are merely listed as alternates with no distinctions drawn. but, except in a very loose sense, these words are not completely synonymous and may not be interchanged indiscriminately. To use these 'synonyms' effectively you need to know considerably more about them than a thesaurus is likely to tell you. With many words—those in the example, for instance—a good abridged dictionary is more helpful... [But] used wisely, [a thesaurus] can improve your working vocabulary.

Bruce Sterling: Roget's Disease. The ludicrous overuse of farfetched adjectives, piled into a festering, fungal, tenebrous, troglodytic, ichorous, leprous, synonymic heap. (Attr. John W. Campbell)

Bill Brohaugh: The word thesaurus has numerous synonyms—so many that you could fill a magazine with them. So many you could fill a warehouse with them. A storehouse, even, or perhaps a treasury, a depository, a repository, an armory, a stockpile, a chest, a compendium, a vault, a hoard, a promptuary, a reservoir... all of which, you have likely guessed by now, are words that you would legitimately find in a thesaurus of thesauri.