Oxford English Dictionary (Bowdoin subscription)
The Oxford English Dictionary is the most comprehensive dictionary of the English language. It traces the development of English from approximately 1150 AD up to the present day. The online version of the Oxford English Dictionary contains two separate texts, the complete Second Edition and the New Edition in progress
Visual English Dictionary (Bowdoin subscription)
The illustrations and cutaways from this Visual Dictionary provide extraordinary rich treatment of a wide range of topics from astronomy and the human body to the arts and society. All the computer-generated illustrations are produced to the highest quality and detail. The labelling on all diagrams reflects the very latest terms in use, for subjects as diverse as sport, architecture, computing, and weapons
New Oxford American Dictionary (Bowdoin subscription)
alphaDictionary
This site is linked to more than 500 dictionaries of over 280 different languages.
Roget's Thesaurus
A searchable thesaurus.