Speedboard

n. downhill skateboard, usually built very heavy duty measuring 40-43" with wheel cutouts for large wheels. often mounted drop-through, with the truck baseplate mounted on top of the board.
v. downhill skateboarding, where riders use aerodynamic tucks and crouches to reach speeds as high as 65mph, drifting their boards at turns and footbraking, airbraking, or sliding to stop.