| Mathematical Thesaurus: Defines mathematical words and concepts, and indicates the links between them. | |
| Phrase Finder: Enter a single word and it will return a list of phrases and sayings that are related to the word in some way. | |
| Roget's II - The New Thesaurus: Contains 35,000 synonyms, succinct word definitions and a hyperlinked category index. | |
| Roget's International Thesaurus of English Words and Phrases: 85,000 hyperlinked cross-references, plus proverbs and quotations from classic and modern authors. | |
| Thesaurus.com: Searchable online version of Roget's Thesaurus of English words and phrases. | |
| Wordsmyth: A dictionary and thesaurus in one. Also gives parts of speech and examples for more than 50,000 words. | |
| WWWebster Thesaurus: Searchable online thesaurus from Merriam-Webster. |
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