The Collaborative International Dictionary of English v.0.48:

Franc \Franc\ (fr[a^][ng]k), n. [F., fr. franc a Franc. See
   Frank, a.]
   A silver coin of France, and since 1795 the unit of the
   French monetary system. It has been adopted by Belgium and
   Swizerland. In 1913 it was equivalent to about nineteen cents
   American, or ten pence British, and is divided into 100
   centimes.
   [1913 Webster]

WordNet (r) 3.0 (2006):

franc
    n 1: the basic monetary unit in many countries; equal to 100
         centimes