Roget's Thesaurus was created by Dr. Peter Mark Roget (1779-1869) in 1805, and released to the public in 1852. The original edition had 15,000 words, and has increased in size with each new edition. The [Karpeles Manuscript Library] houses the [original manuscript] in their collection.
In the foreword to the first edition, Dr. Roget described his thesaurus as:
- "It is now nearly fifty years since I first projected a system of verbal classification similar to that on which the present work is founded. Conceiving that such a compilation might help to supply my own deficiencies, I had, in the year 1805, completed a classed catalogue of words on a small scale, but on the same principle, and nearly in the same form, as the Thesaurus now published.
Roget's Thesaurus is composed of six primary classes. Each of these classes is itself composed of multiple divisions and then sections. This may conceptually be seen as a tree contain over a thousand branches for individual 'meaning clusters' or semantically linked words. These words are not exactly synonyms, but can be viewed as colours or connotations of a meaning or spectrum of a concept. One of the most general words is chosen to typify the spectrum as its headword, which is indexed for the whole group.