Roget’s Thesaurus is an English language thesaurus created by Peter Mark Roget in the 19th century. It was first published in 1852 and contained some 15,000 words. Subsequent editions have enlarged on this.
Although there are other thesauri, the term Roget is often almost synonymous with thesaurus (in much the same way as the brand name Hoover is synonymous with vacuum cleaners). Since first being published it has never been out of print.
In essence, the book groups words according in semantic fields so one might look up teacher and find a number of synonyms; then words associated with teaching,etc. This method of grouping words like this according to their meaning goes back to Aristotle although Roget based his work more on the classifications of Leibniz.
There are a number of editions of Roget’s currently available in different formats.
Roget’s Thesaurus – on Amazon.com
Roget’s Thesaurus – on Amazon.co.uk