rap·pel 
(r
ă-p
ĕl
)
n. A descent from a height, such as a cliff or wall, in which one slides down an anchored rope and applies friction to control one's speed, either by means of a specialized device or by passing the rope under one thigh and over the opposite shoulder.
intr.v. rap·pelled,
rap·pel·ling,
rap·pels To descend from a steep height by this method.
[French, recall, return, rappel, from Old French, recall, from rapeler, to recall : re-, re- + apeler, to summon; see APPEAL.]

rappel