You've probably seen the advert for BT Infinity ("The internet in an instant"). It starts with an explosion of light in outer space, then cuts to some street dancers under a railway bridge, a child trampolining while inexplicably sporting a fox's mask, a prancing white horse and an elderly couple drinking champagne (on a boat?). This all happens to the sound of a folky backing track: "Doo-doo-doo-doo". Tingly, supernatural, futuristic. I think that's what they were going for.

Soon, the shafts of light are plunging into people's homes and cars. The white horse goes a bit bonkers, as you would if there were white beams spearing the earth around you. The beams represent BT's new fibre-optic broadband. The voice-over, breathless with anticipation, tells us that "our internet is changing".

Infinity. It's a bold claim, implying that the service will go on for ever and has literally endless scope. Infinite is overused generally. A newspaper article recently referred to Tiger Woods's "infinite" number of mistresses, which, even by his standards, is pushing it. It's laziness, a casual approach to words when what you want to say is "a lot".

BT, however, has a brand. It will have brainstormed this name. ("Guys, I've got it. We want people to think this is basically the biggest thing ever. Like, there's never been anything bigger. Ever. So, I present you with: Infinity!" Cue chest bumps round the boardroom table.)

But then it undermines the meaning of the term in its very own advert. "BT are investing in our digital future by starting to roll out fibre-optic broadband," says the breathless voice. Starting? That doesn't sound very infinite. It turns out you can get this broadband in certain areas, but not in others.

BT says that about 40 per cent of the population will be able to access the service by the end of the year. That's the least infinite thing I've ever heard. I suppose the company uses the phrase because it sounds epic and exciting. But where does it go from here? What, once you've got a base of "infinity", do you call your next hi-tech, whizzy invention. BT InfinityPlus?

Sophie Elmhirst is features editor of the New Statesman

This article first appeared in the 05 April 2010 issue of the New Statesman, GOD