The Oxford English Dictionary is the pre-eminent dictionary of the English language, with authoritative definitions of more than 500,000 words. In addition to current definitions, it traces the development of words - thus readers of earlier texts turn to the OED to find out what words meant at different periods. Entries include etymologies and quotations - drawn from literary, historical, and scientific sources - illustrating a word's meaning and use.

The OED Online is based on the second edition of the printed work and its three-volume Additions series, and also incorporates draft material and revisions for the third edition (projected to be completed in 2010). The online version allows searching of the entire text of the dictionary - that is, one can search not merely for "head words" (the words being defined), but also for words used in definitions, etymologies, and illustrative quotations. One can also search by the author of quotations (more than 29,000 Shakespeare quotations!), and search for full phrases.

Every quarter, a range of entries in OED Online will be replaced by updated versions produced by the OED's revision programme. New entries will also be added across the alphabet.

Adobe Acrobat Reader needed for help documentation only.

Every screen features a Help button (in the lower right corner of the screen), which leads to detailed and useful information on searching and interpreting. The OED Online Quick Reference Guide and Help with using OED Online are also provided in PDF format.

There is also a very detailed 'Worksheet' for university level use and a 'Tour of OED Online.'