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Wiktionary
base jumping

n. (context sports English) An extreme sport consisting of jumping from a fixed structure on land, using a parachute vb. (present participle of BASE jump English)

Wikipedia
BASE jumping

BASE jumping, also sometimes written as B.A.S.E. jumping, is parachuting or wingsuit flying from a fixed structure or cliff. "BASE" is an acronym that stands for four categories of fixed objects from which one can jump: building, antenna, span, and Earth ( cliff). Due to the lower altitudes of the jumps, BASE jumping is significantly more dangerous than skydiving from a plane. In the U.S., BASE jumping is currently regarded by many as a fringe extreme sport or stunt. In some jurisdictions or locations, BASE jumping is prohibited or illegal; in some places, however, it is permitted, like Perrine Bridge, in Twin Falls, Idaho, USA. BASE jumping became known to the wider public by depictions of BASE jumping in a number of action movies and was featured in the 2014 documentary "Sunshine Superman".

Usage examples of "base jumping".

They were always interested in stuff about cave diving, BASE jumping, snowboarding, hang-gliding, ATB and so on: but they didn't want to know about rock climbing.