!t felt more like a publicity launch for a new Sony PlayStation or Apple's latest Powerbook. There were satellite video links with software executives in America. Key speakers in smart suits eulogised about a global English language shaped by the internet. There were dizzying projections about how many billions of us would speak English in 2050. It was all very slick, terribly hi-tech.

And the product at the heart of so much hype? A plain, old dictionary. To be precise The Encarta World English Dictionary, launched by Bloomsbury, the publishers, and Microsoft last week in book and CD-Rom form.

Yet the content was, well, just what you'd expect from a dictionary: lots of words and as many definitions. Poor old Samuel Johnson would have been baffled by the sheer bravura of the occasion. After all, the inventor of the original English dictionary was the first one to admit that it was not a product one should ever get too excited about. In Dr Johnson's 1755 Dictionary of the English Language, his definition of the word "dull" read, prosaically: "To make dictionaries is dull work".

These days, though, dictionaries rely on promotion which means, ideally, a little controversy each time a new edition is published. Each new revamped edition hopes to stir up discussion, with the aid of some research at the time of publication, about the shifting use of the English language. Whenever the latest Oxford, Collins or Chambers appears, some fusty critics are wheeled out to bemoan the demise of the Queen's English and the inclusion of words like "hammered" and "kalied" (for those about to reach for their dictionaries of slang, they both mean to get drunk).

But the real war of words has shifted away from the cultural critics to the dictionary publishers themselves. They are all desperate to define themselves as unique products and keen to downplay their competitors' niche. Lorna Sinclair Knight, publishing director of Collins Dictionaries, explains: "There used to be two or three major players and now there are around four, all clinging on to smaller chunks of the market."

According to Bookseller magazine, last year's sales for language titles (all phrase and reference books) earned pounds 24.9m, or 2.9 per cent of all book sales. Within the sector, the Oxford English Concise was the biggest seller, earning around pounds 500,000 in revenue - it is currently number two in the bestseller lists. This glut of updated editions is also a response to the speed with which new words fall into common parlance, thanks to the internet, where 95 per cent of the web pages appear in English.

This summer in particular has seen a battle for dictionary supremacy, each one claiming to be the oldest, newest, most established, most trusted or most innovative reference book on the market. The latest Collins Concise Dictionary appeared in June while Encarta followed last week on the same day that the Oxford English Dictionary (OED) renewed a plea for contributions from English-speakers worldwide. Its publisher, Oxford University Press, is busily revising an edition for 2010 - the first complete revision in its history and projected to cost pounds 35m. Even Lonely Planet got in on the act last week with their equivalent offering, The British Phrasebook, an entertaining collection of British slang, including 60 words for getting drunk and about as many for throwing it all up again.

Microsoft and Bloomsbury are trumpeting the Encarta dictionary as unique in the way it defines words and phrases from a global rather than an historical perspective; as opposed to the OED, which first defines the root and history of a word (etymological) before giving its current or global meaning.

Kathy Rooney, Bloomsbury's publishing director, says its product is a response to the worldwide dominance of English and the effects of multi- culturalism. She estimates that by the year 2050, over half of the world's population of 7.96 billion will have competence in English. It's a big market and one that constantly renews itself - every year a new generation of GCSE pupils, university students and scholars will purchase a dictionary and since we're so aware that language is changing fast, there's more incentive constantly to update old copies - well, that's the marketing logic anyway.

Rooney says of Encarta: "We started our project from scratch and have taken a snapshot of the hugely varied language English is today. They are definitions written with a world perspective, and this is the English dictionary to do that." Brave talk and convenient too, that this global product is attached to Microsoft. In CD-Rom form, users can access the dictionary while working in any computer software program, including web browsers.

Penny Silva, deputy chief editor of the OED, which relies on a worldwide source of 10 million words for its research, predictably remains sceptical about Encarta's claims of creating a unique product. "It's nonsense to say they're the first people who have noticed the global use of English. We're all more conscious about viewing English as an international language. There seems to be a slant towards American culture in Encarta, though, and a huge slant to IT electronics as well."

Collins, too, is sniffy about the newcomer on the block. After all, Encarta has muscled in, rather, on its unique selling point. Unlike the OED, it prides itself on defining a word's current use rather than its history first. Diana Treffry, editorial director for Collins English Dictionaries, says: "Encarta isn't promoting anything new. It's been well recognised that there are all sorts of vibrant versions of English that contribute to one another. Collins uses an enormous computer bank of 323 million words collected from newspapers, books, magazines - all areas - to use as evidence to include certain words."

If there are any shifts in the ways that dictionaries respond to the English language it is the general move from prescriptive to reflective. When Dr Johnson first published his Dictionary of the English Language he hoped to record the best that had been written and thought. Now the role of most dictionaries is to record what is used most commonly and to keep up with the pace of change. As Ms Treffry says: "It is no longer a rule book of what you can and cannot use. We simply describe what is going on."

Lonely Planet appears to have taken this guiding principle one step further than the more traditional lexicographers in the field. In its British Phrasebook, it says: "If you want to appear cool you salt your native tongue with words like cool and rock and super and mega, you call jeans jeans and trainers trainers and you say fuck a lot, the most internationally understood English word aside from OK and bar." Encarta clearly bore this in mind when it decided to select six entries in their F section, whereas OED contains a conservative two.

Overall, though, there's far less difference between all the dictionaries than they would care to make out. After a quick skim through Collins, Encarta and OED, the distinctions in definition or words included, to the layman's eye at least, seemed negligible. None of them can claim to be the definitive dictionary, though; it's just a matter of which brand you prefer. Perhaps Dr Johnson knew best when he said: "Dictionaries are like watches, the worst is better than none and the best cannot be expected to go quite true."