tesaurus

Tesaurus is a reference work that lists words grouped by meaning, typically providing synonyms and sometimes antonyms. Its main purpose is to help writers expand vocabulary, choose more precise terms, and avoid repetition. Unlike a traditional dictionary that emphasizes definitions and usage notes, a tesaurus focuses on relationships between words, though many modern editions include brief senses to aid selection and notes on connotation or part of speech.

Origins and scope: the best-known example is Roget's Thesaurus, first published in 1852 by Peter Mark Roget. Since then, thesauri have been produced for many languages, in print and digital formats. They can be monolingual (one language), bilingual, or multilingual, and they may specialize in particular domains such as science, law, or literature.

Structure and content: entries are typically organized by concept or sense, with cross-references to related terms and sometimes lists of antonyms. Some editions include usage guidance, frequency information, or collocation notes to help preserve natural phrasing.

Applications and limitations: in writing and editing, thesauri support paraphrasing and style variation; in language learning and natural language processing, they underpin synonym replacement and semantic similarity tasks. A major limitation is that synonyms are not interchangeable in all contexts; connotation, formality, and collocation matter, so careful selection is required. Digital thesauri may be linked to linguistic resources such as WordNet or corpus data to enrich semantic relations.

See also: Thesaurus, Roget's Thesaurus, WordNet.