The Oxford English Dictionary (OED) is widely regarded as the accepted authority on the English language. It is an unsurpassed guide to the meaning, history, and pronunciation of 600,000 words past and presen from across the English-speaking world. As a historical dictionary, the OED is very different from those of current English, in which the focus is on present-day meanings. You'll still find these in the OED, but you'll also find the history of individual words, and of the language—traced through 3 million quotations, from classic literature and specialist periodicals to films scripts and cookery books.
Oxford Music Online is the access point for Grove Music Online, Encyclopedia of Popular Music, The Oxford Dictionary of Music, and The Oxford Companion to Music