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Title page of Roget's Thesaurus of English Words








“Though it is the first work of its kind that has appeared in the history of our language, the completeness of its plan, and its fullness of detail, are such as to leave little to be supplied by others.”

– Barnas Sears (editor), Preface of the American Editor

Title: Thesaurus of English Words, so Classified and Arranged as to Facilitate the Expression of Ideas and Assist in Literary Composition

Author: Peter Mark Roget

Printed: Boston: Gould and Lincoln, 1854

First American Edition

Call Number: PE1591 R7 1854

First page of index in Roget's Thesaurus.









Did you know January 18th is Thesaurus Day? You may be wondering how one celebrates Thesaurus Day. It’s simple. You just open a thesaurus.

A thesaurus is a reference work that lists the synonyms and sometimes antonyms of words. The first thesaurus was created when British doctor and mathematician Peter Mark Roget developed an index of synonyms to aid him in his writing projects. He began collecting synonyms in about 1805 and by 1840 had decided that his index may be of interest to others. He retired from medicine and devoted the remainder of that decade to preparing his indexed collection of synonyms for publication.

Roget’s Thesaurus was released on 29 April, 1852, containing 15,000 words. The second edition was published in 1853. The first American edition followed in 1854. Over the past century and a half, numerous editions have been released and Roget’s Thesaurus has never been out of print. Over 32 million copies have been sold worldwide. Its impact on writing is immeasurable.

In the introduction to the first American edition, Roget explained:

“The present work is intended to supply, with respect to the English language, a desideratum hitherto unsupplied in any language; namely, a collection of the words it contains and of the idiomatic combinations peculiar to it, arranged, not in alphabetical order as they are in a dictionary, but according to the ideas which they express.”

Roget’s Thesaurus is composed of six primary classes. Each class is composed of multiple divisions and then sections. This may be conceptualized as a tree containing over a thousand branches for individual “meaning clusters” or semantically linked words. Although these words are not strictly synonyms, they can be viewed as colors or connotations of a meaning or as a spectrum of a concept. One of the most general words is chosen to typify the spectrum as its headword, which labels the whole group.

Roget’s schema of classes and their subdivisions is based on the philosophical work of Leibniz (symbolic thought), itself following a long tradition of epistemological work starting with Aristotle. Some of Aristotle’s Categories are included in Roget’s first class “abstract relations.”

The classification system of Roget's Thesaurus.








PE-1591-R7-1854-pg 16 17 spread







Although the classification system Roget chose to use in his Thesaurus may seem abstract, without the decision to share his index with the world, writers (and speakers!) across the globe would not have benefited over the past century and a half from this wonderful literary tool. So on this Thesaurus Day let’s open the nearest thesaurus and take a look. Who knows, you may even have a copy of Roget’s Thesaurus on your shelf, long forgotten, but ready to assist you should you need to find just the “right”* word.

*correct, accurate, exact, precise, legitimate

-Contributed by Jon Bingham, Rare Books Curator