The ARTFL Project
The American and French Research on the Treasury of the French Language site conjugates French verbs, translates English to French or French to English, and searches the 1913 and 1928 Webster's dictionary and the 1911 Roget's Thesaurus.
Free access to definitions helpful to individuals learning English as a Second Language.
One of the largest online dictionaries also offers a thesaurus, an encyclopedia, a translation page, and quotation searching.
Merriam-Webster Language Center Online
Look up words in either the Collegiate Dictionary or Collegiate Thesaurus. Spanish-English translations and a medical dictionary are also provided.
Indexes over 19 million words in over 1,000 online dictionaries.
Online Etymology Dictionary
Combines information from many scholarly resources on language to provide the history and derivation of words.
Roget's International Thesaurus at Bartleby.com
Contains 85,000 hyperlinked cross-references and 2,900 quotations.
Do a simple word search or use links to find out more about words at this site.
WordNet: A Lexical Database for the English Language
This is a free dictionary and thesaurus of English words that provides definitions, synonyms, antonyms, hyponyms, metonyms, homonyms, derived forms and sample sentences.
Searches more than 2,500 dictionaries and grammars in over 300 languages.