1. a book or electronic resource that lists words in groups of synonyms and related concepts: "I'm going to need a thesaurus to come up with synonyms for ‘stupid’"
▪ a dictionary or encyclopedia.
Word Originlate 16th century: via Latin from Greek thēsauros ‘storehouse, treasure’. The original sense ‘dictionary or encyclopedia’ was narrowed to the current meaning by the publication of Roget's Thesaurus of English Words and Phrases (1852).
