Peter Roget was born on this day in 1779. Thesaurus Day celebrates the birthday of the author of Roget's Thesaurus. The Thesaurus has been an invaluable reference book for hundreds of years. Students and writers use it to improve the quality of their literary work. After High School, many if uf forget. So you're in good company. The Thesaurus lists synonyms for words. It allow you to avoid repetition in writing and speeches. So if you wear a wristband with the messsage "Thesaurus Day" you will never forget this day.