What is a thesaurus?

A thesaurus is a reference work that lists words grouped together according to similarity or relatedness in meaning, often in the form of synonyms and antonyms. Thesauruses are commonly used by writers, students, and language learners to expand their vocabulary, find the right word to express their ideas, and avoid repetition in their writing. Thesauruses can be in printed form or accessed online, and typically include additional information such as usage examples, context, and connotations of words. While a dictionary provides definitions and spellings of words, a thesaurus focuses on the relationship between words and the nuances of meaning.