thesaurus
Thesaurus (noun) means a reference book or website that groups words by meaning, so you can look up a word and find its synonyms and often its antonyms. Example: “I keep a thesaurus open when I'm editing to avoid repeating myself.”
How to Use Thesaurus
Learner’s notesIn plain EnglishA book or site that gives you other words meaning roughly the same thing.
Neutral. The plural is thesauruses in ordinary use and thesauri in more formal or academic writing; both are accepted.
A thesaurus tells you what else you could say; a dictionary tells you what a word actually means. Always check an unfamiliar synonym in a dictionary before using it.
Trace the full origin ↓Fill the Gap
Can you complete this real example?
I keep a _____ open when I'm editing to avoid repeating myself.
Etymology
From Latin thesaurus 'treasure, treasury, storehouse', from Greek thesauros.
Synonyms
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Rhymes for thesaurus
See all rhymes for thesaurus →Frequently Asked Questions
What is the difference between a thesaurus and a dictionary?
A dictionary is organised by headword and tells you what each word means, how it is pronounced and where it came from. A thesaurus is organised by meaning and gives you alternative words that express a similar idea. Writers use both together — the thesaurus to find a candidate, the dictionary to check it fits.
What is the plural of thesaurus?
Both thesauruses and thesauri are correct. Thesauruses is more common in everyday English; thesauri keeps the Latin plural and appears more in academic and library contexts.
Why is it called a thesaurus?
The word is Latin for treasury or storehouse, itself from Greek. The idea is a store of words you can draw on, and the sense of a hoard of treasure is the older meaning of the Latin term.