A full-size van, usually with a completely re-done interior and some external modifications, all of which are done by a company who buys the van new and then re-sells the vehicle to consumers. These add-ons can include everything from blinds to a tv. They almost always have a fiberglass roof that is taller than stock, to make head room and add room for the tv. Many of these vans come stock with middle row seats that rotate, and a back seat that folds into a bed. There are many other great things about conversion vans too.
My friend has got a Honda Odyssey, which has a V6, a TV, lots of storage, and automatic doors. I have a Chevy G20 conversion van, which has a V8, is rear wheel drive, has a TV, even more storage, tons of leg room, and automatic doors are for sissies.