n. A sport in which a person is strapped inside a large sphere which is itself held inside a larger sphere by a cushion of air, and then rolled down a hill or along the ground.
Other Forms
Ball nuts have a new outlet for indulging spherical fantasies — zorbing. Brought to you by the sensory-deprived souls who gave us bungee jumping and river sledging, New Zealanders with too much downtime, zorbing takes you into the game of globular physics. You are no longer a ballplayer; you are the ball. The sport involves the insertion of a human into the inner sphere of a giant double-skinned orb with air holes. A roll down a hillside sets off involuntary Olympics-style tumbling within. If you've ever wanted to flip like Mary Lou Retton or spin with the wild abandon of sneakers in a Maytag, zorbing may be your thing. No skills required, other than ability to hold down food.
—“Let it roll,” Los Angeles Times, October 28, 2003
The latest zorb — made to look like a pumpkin — was completed this week and is on its way to wow the crowds at Euro Disney's Halloween celebration.

Invented almost 10 years ago by Andrew Akers and Dwane van der Sluis, zorbing is now a global business with agents and franchisees in many countries. …

Hydro-zorbing is the latest development.

The passenger is not strapped in but left to flail about as the zorb floats across water.
—Ellen Read, “Zorb inventors rolling in it,” The New Zealand Herald, August 15, 2003
1996 (earliest)
What is it with New Zealand? Just when we had got used to bungee jumping from helicopters, they have come up with a new way of pumping the adrenaline: zorbing. We are reliably informed this involves climbing inside a giant perspex sphere and being rolled down a mountainside. If the place is that short of excitement, wouldn't it be easier to emigrate?
—Mark Hodson, “Roll with it,” Sunday Times (London), April 21, 1996
See zorb.com for more information and lots of pictures.