The four-letter word that nobody dares speak...

London International Mime Festival: a mouthful of a name to conjure with, and its founder Joseph Seelig knows it. He's lost count of the times he's toyed with changing the title, and not just because the PR company protests that the word mime is a major turn off. The main problem is that mime is not what this festival is about.

"When we started 25 years ago all the acts in the festival were mime," he reasons, "but that soon changed. For a long time now it's been a festival of visual theatre drawn from all over Europe and beyond – a collection of uncategorisable shows linked only by the fact that they have relatively little text. But visual theatre is two words and mime is one, and once we'd got going there seemed little point in changing. Our audience knew we were doing something different and we felt that was enough." He uses the word uncategorisable with feeling. He's tried, he's really tried, to find a snappy way to talk up this year's opening show, Gopf, which opens at The Place on Friday. Kafkaesque architectural fantasy? A sliding jigsaw show? Kind of. More telling, perhaps, to reveal that of its three Swiss performers one is a graduate of the French National Circus School, another a former principal of Bejart Ballet, and the third a club DJ who, perched atop an extraordinary set with his six turntables, controls events like a 21st-century puppet master.

Another case in point is Circus Ronaldo, from Belgium, one of this year's headline acts at the Queen Elizabeth Hall. The experience is not really circus, nor theatre, but best approximates to being invited into the bosom of a family that lives and breathes the spirit of commedia dell'arte. Though there is indeed juggling, a balancing act, and the funniest bicycle gag since Jacques Tati, the lasting impression is of entering a Felliniesque fantasy, complete with a fondness for naked flame that will already be giving the South Bank's fire inspector sleepless nights.

Another odd feature of Circus Ronaldo is that its performers speak – not in Flemish, their native tongue, but in a language the playwright Dario Fo has christened "grammolo". This is the Italianate gobbledegook developed by travelling players in the 17th century when they wished either to speak and not be understood (so as to avoid censorship), or conversely, to give the impression of nonsense while conveying surreptitious meaning. You have to experience grammolo in action to appreciate how it works.

In recent years Belgium and France have featured strongly in LIMF programmes. These countries not only have a long tradition of country fair entertainment, Seelig explains, but in the last 10 years the French Government has invested heavily in circus skills. Previously the lion's share of physical theatre talent came from Eastern Europe, particularly the former Czechoslovakia. "Under Communism it was useful to say things without words," he says. "But since the end of that regime the whole area of visual theatre has collapsed in that part of the world. Now some of the finest work we show comes from Britain." Could that be because we're becoming more European? Not necessarily, in Seelig's opinion. "Things go in cycles and this is perhaps not an age of great writing for the theatre. One can't underestimate the impact of television and advertising. Increasingly people receive their information in a visual way; they're accustomed to looking for visual meaning. That's having a knock-on effect across a whole range of theatre – even at the National and RSC." Although proud of its position at the experimental end of the spectrum, Seelig is equally pleased to list the festival's mainstream successes. Theatre de Complicite is one ("when they started as an English company with a name nobody could pronounce, the Mime Festival was its natural home"); The Right Size, currently in the West End with their Morecambe and Wise show The Play Wot I Wrote, is another. Andrew Dawson – co-creator of the West End hit Thunderbirds FAB – features once again in this year's line-up with an autobiographical piece about the death of his father.

Seelig is probably right. The Mime Festival has survived and flourished precisely because it's so hard to pin down. It has even managed to thumb the nose at "that very big, very glamorous circus down the road", which hasn't proved nearly such a threat as you'd expect. When Cirque du Soleil first came to London in the mid-1990s, Seelig feared it would gobble his audience overnight. It hasn't, partly because, as he says, "you can practically see our entire festival for the price of an ice cream at the other place", but also because there will always be an audience out there for artistry and entertainment on a more intimate scale.

The 25th London International Mime Festival runs from Friday to 26 January at various venues. Full details can be found at www.mimefest.co.uk. For a brochure, call 020 7637 5661