BASE jumpingBASE jumping, base jumping /ˈbeɪs ˌdʒʌmpɪŋ/ noun [uncountable] 
(Building, Antenna, Span, Earth) a sport in which people jump off tall objects such as buildings, bridges, or cliffs, using a parachute
(Building, Antenna, Span, Earth) a sport in which people jump off tall objects such as buildings, bridges, or cliffs, using a parachute