The name given to small silver coins struck at Freiburg in Breisgau in the fourteenth century, on account of the head of a raven on the obverse, which was copied from the arms of the city. Raben was later corrupted into Rappen (q.v.).
See Also: Denarii Corvorum
Source: Frey's Dictionary (American Journal of Numismatics, Vol. 50, 1916)