An Etymological Dictionary of the German Language/Annotated/Riff

by Friedrich Kluge

Riff, neuter, ‘reef,’ Modern High German only, from Low German riff, reff; compare the equivalent Dutch rif, neuter, English reef, and Old Icelandic rif. The latter is equivalent in sound to Gothic rif, ‘rib,’ but this is probably only an accident. It has been thought to be allied to Old Icelandic rífa, ‘to slit, split,’ rifa, ‘rift, split’; hence probably Riff means literally ‘the dissevered, cleft, mass of rock,’ then ‘reef.’