Here’s How New Words Get Added to the Thesaurus

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The book that saves your writing when you’re stuck has a story all its own. Here’s what you never knew about your trusty thesaurus.

Pull out your dog-eared copy of Roget’s Thesaurus (if you have one!) and marvel at its innovation. Thesauri, or thesauruses, have been around in various forms since antiquity. The word thesaurus actually derives from the Greek thēsauros, meaning both a treasure or treasury and a storehouse. The etymology of the word perfectly captures the endeavor at the heart of these compendiums: A thesaurus offers synonyms, words that are related and similar but not precisely the same.

So, do you consider your thesaurus a treasure? Something valuable to add rich nuance to your writing? Or is it merely a storehouse of alternate words for you to choose from when you feel like you’re repeating yourself? Either way, you can’t deny that it’s useful. But where do all those helpful alternatives come from? And how can you best utilize them? We’re so glad you asked!

Is your thesaurus only for finding the right word?

The first edition of Roget’s Thesaurus, published in 1852, wasn’t arranged in alphabetical order. Instead, it was organized topically or, if you want a big, shiny, impressive word, onomasiologically! It was cataloged by categories and themes with an elaborate index in the back. Peter Mark Roget, who was a philosopher as well as a scientist and inventor, intended the collection to “facilitate the expression of ideas.” Linguists and scholars find the first English thesaurus to be much more than a reference book—it’s also a discourse on the complexity of experience and ideas. As B.D. McClay writes for The Outline, Roget “was showcasing and organizing language.” McClay explains that thesauri allow “the ability to see words not simply as isolated bits of vocabulary, but as parts of a bigger way of thinking and associating ideas and meaning.”

The latest editions of Roget’s Thesaurus, and other traditional thesauri, are still organized by theme or category. This structure gives readers immersion into a word’s meanings as they connect and relate to a range of ideas. Popular thesauri, primarily used for writing students, arrange alphabetically and offer a list of synonyms. Here are 50 words you think are synonyms but aren’t.

How are new words added to the thesaurus?

Lexicographers, linguists, and language scholars and experts work on thesaurus entries. There are many different kinds of thesauri covering different disciplines and languages. Thesaurus writers and editors study words and their definitions, but they also need to examine a word in its natural environment. That is, they need to read “in the wild.” Since language morphs and shifts along with culture, there are constant revisions and updates to reference works—including the dictionary and thesaurus. Thesaurus writers scour written material to discover not only new words but also new meanings and new shades of meanings, and they update new editions accordingly.

For example, the seventh edition of Roget’s International Thesaurus, edited by Barbara Ann Kipfer, PhD, and published in 2011, boasted 2,000 new words and phrases (like “alpha male” and “zero tolerance”) that reflected language changes in culture. In addition, the volume dropped “archaic terminology.” This edition holds to Roget’s original structure, with an alphabetical listing in the back and the front matter arranged by theme and category. The first Roget thesaurus contained 15,000 words. This Kipfer edition, which contains Roget’s original preface, contains more than 320,000 words in its 1,300-plus pages. The eighth edition, which came out in November 2019, is up to 443,000 words and phrases grouped into 1,075 categories (though Amazon reviewers apparently don’t love the new indexing system). But believe it or not, that’s actually not that many compared to some thesauri out there. Are you a word nerd? Here’s how words get added to the dictionary.

The Historical Thesaurus covers 800,000 English words

Assembling the Historical Thesaurus of the Oxford English Dictionary (which looks at the English language across 1,300 years) took more than four decades to complete before it was published in 2009. The massive volume gathers words into 236,000 categories under three main umbrella terms: the External World, the Mind, and Society. According to Henry Hitchings writing for the Telegraph, “These are broken down into less broad domains: the External World is divided into the Earth, life, physical sensibility, matter, existence, relative properties, and the supernatural.” Hitchings explains that the tome offers a detailed consideration of words. In his example of finding a synonym for dirty, he discovers hog, daggle-tail, and scrubber, each term employed centuries apart but conveying the same general idea.

Scholars have been working on a Latin thesaurus for more than a century

Lexicographers have been compiling entries for the Thesaurus Linguae Latinae since 1890, and they don’t plan to finish until 2050. They’re composing a volume for every letter of the alphabet, and as of 2019, they’re only up to “R”—with the letters “Q” and “N” set aside due to their length and difficulty. Latin scholars will turn to those volumes eventually as they create detailed “biographies” for each Latin word in use since ancient times. The historic volume seeks not to define the word, but to record “every single way anyone ever used it.” This sprawling compendium also includes “branching trees,” which depict how that word relates to others. Marissa Fessenden at Smithsonian Magazine writes that “every new shade of meaning a word gathers deserves its own branch.”

Use a thesaurus when you’re looking for nuance

Consult your thesaurus when you’re looking to capture a precise shade of meaning. The synonyms in a thesaurus will not have the exact same meaning as the word in the entry. Instead, they’ll offer overlapping or linking meanings. Use the thesaurus when you’re looking for nuance in a word—spice, precision, or distinction. Roget himself advised readers to “select the most appropriate expression.” The right word can make your writing sing, while the wrong one makes it squeak. Think of your thesaurus as a way to help you express your thoughts and ideas with eloquence. Don’t choose a word to be impressive, cryptic, mysterious, or obscure. What word do you always look up? Here are the 20 synonyms people search for the most.

You’ll need your dictionary to use a thesaurus correctly

If you’re using an alphabetical thesaurus, you’ll look up a word and find an entry filled with synonyms. You can gauge the general meaning of the word you looked up from the synonyms, but you don’t get an official definition in a thesaurus. Thesauri often get a bad rap because while they give you a variety of choices, they often serve up a word that doesn’t quite fit or seems out of place. You should always use your dictionary to find the official definition of the word you’re using and the one you’re replacing it with. Make sure you’re on the right track—and not taking your sentence off the tracks. Check out these hilarious examples of thesaurus use gone wrong.

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Molly Pennington, PhD
Molly is a writer and professional astrologer with a PhD in Critical and Cultural Studies from the University of Pittsburgh. She covers the zodiac, books, movies, TV, and culture for She loves puns, puzzles, people, the planet Mars, and philosophizing.