1931, "mountaineering technique for descending steep faces," from French rappel, literally "recall" (Old French rapel), from rapeler "to recall, summon" (see repeal (v.)). The same word had been borrowed earlier (1848) to mean "a drum roll to summon soldiers."
rappel (v.)
1957 in the mountaineering sense; see rappel (n.). Related: Rappeled; rappelling.
rapids
rapier
rapine
rapist
rapparee
rappel
rapper
rapping
rapport
rapportage
rapporteur