To communicate a message or an idea, you need words: not just any words, but words that get your message out with clarity and precision. Words that evoke emotions and create a powerful image. When looking for just the right words to get your message across, a thesaurus is an invaluable tool. The word thesaurus comes from the Greek word thesaurus, which means treasure or storehouse, and that’s what a thesaurus is: a treasure of words.

On January 18 each year, we celebrate National Thesaurus Day. Though the origin and founder of this day are not known, the date was picked in honor of Dr. Peter Mark Roget, who was born on the same date in 1779. Dr. Roget was a physician and lexicographer who was responsible for writing the very first modern thesaurus. It was published in 1852 and was called Roget’s Thesaurus of English Words and Phrases. The book contained 15,000 words and was arranged into six primary categories time, relation, existence, quantity, number, and time. Roget’s Thesaurus is still in use today. It contains over 230,000 words and is organized based on concepts rather than alphabetically.

To learn more about Peter Mark Roget and the creation of the thesaurus, check out The Right Word, written by Jen Bryant and illustrated by Melissa Sweet. Join us as we celebrate National Thesaurus Day and expand our vocabularies using the treasure that is the thesaurus.


The Right Word Roget and His Thesaurus book for childrenThe Right Word

Roget and His Thesaurus
Written by Jen Bryant
Illustrated by Melissa Sweet
Ages 7 and up
ISBN: 978-0-8028-5385-1

Awards for The Right Word include:

  • ALA 2015 Caldecott Honor
  • ALA 2015 Sibert Medal
  • NCTE 2015 Orbis Pictus Honor
  • ALA 2015 Notable Children’s Books

For a full list of this book’s awards, check out this page on the Eerdmans website.

Kirkus prize
Junior Library Guild Selection
National Counsil of Teachers of English
Purchase The Right Word Roget and His Thesaurus from:


The Right Word Jen Bryant and Melissa Sweet Picture Book Discussion GuideDownload The Right Word (Jen Bryant/Melissa Sweet) Picture Book Discussion Guide

Guide a classroom, library, book club, or other discussion of this Caldecott Honor-winning biography of Peter Mark Roget, the creator of the thesaurus. Marked with Common Core language and literature standards, this free downloadable pdf will jumpstart conversations and invite reflection on the book’s themes.

Click here to download