BASE is an acronym that stands for four categories of fixed objects from which one can jump: buildings, antennas (referring to radio masts), spans (bridges) and earth (cliffs).[1][2] Participants jump from a fixed object such as a cliff and, after an optional freefall delay, deploy a parachute to slow their descent and land. A popular form of BASE jumping is wingsuit BASE jumping.
Huh, and here I always thought it was rooted from “jumping from a stationary base” like a building or cliff. Neat!