General reference
Dictionaries, encyclopaedias and open data sources for quick facts and background reading.
Dictionaries
- Merriam-Webster Dictionary and ThesaurusDictionary entries and thesaurus entries, including extensive synonym and antonym lists.
- Oxford English DictionaryThe accepted authority on the English language: the meaning, history and pronunciation of 600,000 words, past and present.
- Cambridge DictionariesPopular dictionary and thesaurus for learners of English, with pronunciations and translations.
- OneLookMore than five million words in more than 900 online dictionaries.
- YourDictionaryAnswers to questions about words and language.
Encyclopaedias
- RefSeekDirectory of the web's best encyclopaedias, including Britannica, Columbia, Reference.com and Wikipedia.
- BritannicaThe Encyclopædia Britannica, a general knowledge English-language encyclopaedia.
- WebopediaOnline dictionary for computer and internet technology, with plain definitions and guides.
- WikipediaA free, open-content online encyclopaedia.
- CIA World FactbookHistory, people, government, economy, geography and more for 265 world entities.