Roget's Thesaurus

Roget 's Thesaurus is a thesaurus of the English language and is considered as one of the most important works of its kind

The first version was completed by the lexicographer Peter Mark Roget in 1805 and published in 1852; it contained 15,000 words, which were divided into six classes. While the name Roget 's Thesaurus in the UK is legally registered as a trademark until today, the name in the U.S. is used freely to describe thesauri, similar to the name Webster (see Merriam- Webster 's Collegiate Dictionary) for dictionaries.