thesauri

A thesaurus, plural thesauri, is a reference work that groups words by meanings and provides synonyms and related terms. Its primary purpose is to help users find alternative words, expand vocabulary, choose precise terms, or vary language.

Entries are organized by sense or concept; there are monolingual, bilingual or multilingual, and domain-specific varieties. Some entries include usage notes, part of speech, formality, and collocations.

History: The first modern thesaurus was published by Peter Mark Roget in 1852, organizing words into conceptual classes, divisions, and sections. Since then, many print and digital thesauri have appeared. In computational linguistics, WordNet (begun in the 1980s) is a large lexical database that groups words into synsets with semantic relations such as hypernyms, hyponyms, and antonyms, and is widely used in natural language processing.

Digital thesauri are integrated into word processors, educational tools, search engines, and NLP pipelines. They support tasks such as writing assistance, vocabulary development, and text analysis.

Limitations: synonyms are not always interchangeable; meaning, connotation, register, and collocation must be considered. A thesaurus complements but does not replace careful reading of dictionary definitions.