Collins English Dictionary has evolved into a glorious great slab of a reference book since its relatively modest first appearance in 1979. The 2003 version, rooted in the Bank of English, a 524-million word database launched in 1991, is the sixth edition.
Strong on clear definitions, derivations, cross-referencing, acronyms, technical and scientific terms and geographical place names, Collins English Dictionary also includes occasional boxed "language notes". Thus, for example, after "mitigate" we are usefully reminded that "Mitigate is sometimes used where militate is meant: 'His behaviour militates (not mitigates) against his chances of promotion.'"
Interestingly, users of English are evidently becoming more relaxed about their language. Seventy words previously deemed taboo are now described merely as slang. Perhaps rows of asterisks will soon be a thing of the past. Language changes continually and so do attitudes to it. There is a distinct sense of celebration in the latest Collins English Dictionary because English is one of the richest and most diverse of the world's languages and it is rapidly becoming a global lingua franca.
Jeremy Butterfield and his colleagues have made a splendid job of recording exactly where English is now. We may need to know what a "sex text" or a "dead-cat bounce" is today but, perhaps, in the quite near future such terms will fall out of use. That's why dictionaries need to be continuously updated, leaving earlier editions as reference works for language historians to study. It's also what makes dictionaries in general and Collins English Dictionary in particular so fascinating and why word lovers need the latest version on their shelves.