NATIONALL THESAURUS DAY is observed every January 18th to honor the man who put together the first true thesaurus, Peter Mark Roget, a British physician and lexicographer.
But what is a thesaurus?
A thesaurus is simply a reference work that contains synonyms (and sometimes anonyms) in a dictionary format. The main purpose of a thesaurus is, in the words of Roget, “to find the word, or words, by which [an] idea may be most fitly and aptly expressed.” Students and writers use a thesaurus to help them find the best word to express an idea.
In antiquity, Philo of Byblos wrote the first text that could now be called a thesaurus. In the 4th century, there’s one in Sanskrit written in verse form. The study of synonyms became important in 18th-century philosophy, and there were various “dictionary of synonymous words” published from 1668, throughout the 1700’s, and early 1800’s. Roget first compiled Roget’s Thesaurus in 1805 and published it in 1852. It has been in continuous print since.
Roget organized his work by grouping synonyms according to similarity of meaning. But unlike earlier versions of thesaurus dictionaries, his does not include definitions or help the user choose among synonyms. Merriam-Webster’s Dictionary of Synonyms does discuss differences. Others include short definitions, or illustrative phrases; some include lists of objects within the category, like breeds of dogs.
So, if you’re looking for a particular shade of meaning in a word but can’t quite grasp it, you might find inspiration in a thesaurus.