Oxford English Dictionary (OED) 
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 present—from across the English-speaking world.
As a historical dictionary, the OED is very different from dictionaries of current English, in which the focus is on present-day meanings. You’ll still find present-day meanings 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 film scripts and cookery books.
The OED started life more than 150 years ago. Today, the dictionary is in the process of its first major revision. Updates revise and extend the OED at regular intervals, each time subtly adjusting our image of the English language.
