Dictionary.com
definitions

BASE jump

or B.A.S.E. jump,or base jump

[beys]
noun
  1. a parachute jump from the top of a building, bridge, cliff, etc., usually at a height of 1,000 feet (305 meters) or less.

Origin of BASE jump

1980–85; B(uilding) + A(ntenna) (tower) + S(pan)1 + E(arth) + jump
Related formsBASE jumper, nounBASE jumping, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for base jumping

base jumping

noun
  1. a sport in which a participant parachutes from any of a variety of fixed objects such as high buildings, cliffs, etc

Word Origin for base jumping

C20: b (uilding), a (ntennae), s (pan, and) e (arthbound object)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012