What was the original title of Roget's Thesaurus?

What was the original title of Roget’s Thesaurus? The answer is Thesaurus of English Words and Phrases.

Peter Mark Roget’s first edition was published in 1852 under the title Thesaurus of English Words and Phrases, Classified and Arranged as to Facilitate the Expression of Ideas. The title described the book’s purpose: helping writers find words by organizing them according to related meanings rather than listing them only alphabetically.

Roget began developing his classification system decades before publication, influenced by his interest in science, medicine, philosophy, and the systematic arrangement of knowledge. The first edition grouped words into broad conceptual classes, divisions, and sections. It was therefore more than a simple list of exact synonyms.

That distinction explains a frequent misunderstanding. A thesaurus may place near-synonyms, related terms, contrasts, and words with different shades of meaning together. Roget’s work became a model for later thesauruses, while the name “Roget” eventually became strongly associated with synonym dictionaries in popular usage.