Includes the Oxford English Dictionary, and the Historical Thesaurus of the OED, which contains almost the entire vocabulary of English, from Old English to the present day. Also offers publicly available editorial features, providing guides to the OED content and regular commentaries on topical issues in the story of the English language.
The illustrations and cutaways provide a rich treatment of a wide range of topics from astronomy to the human body to the arts and society. The Visual Dictionary provides a perfect way to explore topics that are difficult to explain in words.
New Dictionary of the History of Ideas
Mosby's Medical Dictionary by 
