Pumptrack
Also known as: pump track
A closed loop of rollers and banked turns where you build speed by pumping, never pushing.
Extended definition
A pumptrack is a continuous circuit of mounds and banked corners designed so you never put a foot down: speed comes purely from pumping your body through every roller and berm. It works for skate, BMX, scooter and MTB, and it's exploding in public parks because it's cheap to build and addictive to ride. It's also the single best way to actually feel what pumping is.