OED a very large dictionary of English, started in the 1880s, which is famous for its completeness and for its explanations of the origins of words and their history. It is available either as a book in several large volumes, or as a CD-rom
Definitive historical dictionary of the English language. It was conceived by London's Philological Society in 1857, and sustained editorial work began in 1879 under James Murray. Published in 10 volumes between 1884 and 1928, it first appeared under its current name in 1933. Its definitions are arranged mostly in order of historical occurrence and illustrated with dated quotations from English-language literature and records. Its second edition was published in 20 volumes in 1989