half-pipe

or half pipe

[ haf-pahyp, hahf- ]
/ ˈhæfˌpaɪp, ˈhɑf- /

noun

a half-moon-shaped chute or ramp used by snowboarders and skateboarders to provide a takeoff for a jump.

British Dictionary definitions for half-pipe

half-pipe

noun

a structure with a U-shaped cross-section, used in performing stunts in skateboarding, snowboarding, rollerblading, etc