Thesaurus Day

Thesaurus Day is an American holiday celebrated annually on January 18. This special day honors the thesaurus—a valuable resource for anyone looking to enrich their vocabulary, better understand their native language, and expand their horizons.

History

The origins of thesauri go back many centuries. One of the earliest works resembling a modern thesaurus is the *Amara-kosha* in Sanskrit, created in the 6th century and presented in poetic form.

The first modern thesaurus is widely considered to be the one compiled by Englishman Peter Mark Roget in 1805. Although he completed his work in the early 19th century, it was first published in 1852. Roget’s Thesaurus has remained in print in various editions ever since.

In the second half of the 20th century, as computer technology advanced, thesauri became essential for information search and analysis tasks. Today, they are even used in artificial intelligence applications. Unlike classical dictionaries, a thesaurus not only defines words but also provides synonyms and related terms, offering a richer understanding of language.

Interesting Facts

• Microsoft Word features a built-in thesaurus to help users find synonyms and enhance their writing.
• In psychology, the term “thesaurus” can refer to an individual’s unique way of processing and interpreting information.
• A thesaurus is not the same as a dictionary—a thesaurus groups words by similarity in meaning, while a dictionary lists and defines words.

How to Take Part

Spend some time exploring a modern thesaurus on Thesaurus Day to discover new words and enrich your vocabulary. You might also look up historical thesauri to see how language has evolved over time.

Share interesting new words or synonyms you learn on social media. Start a conversation about the significance of language and how building your vocabulary can broaden your perspective.

When is Thesaurus Day in 2026?

Thesaurus Day is observed on January 18 each year.

Observations