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

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "franc":
   Deutschmark, Mark, Reichsmark, afghani, anna, baht, cent, centavo,
   centime, conto, dollar, dong, florin, guilder, gulden, kip, kopeck,
   krona, krone, lira, milreis, peseta, pie, piece of eight,
   pistareen, pound, rand, rial, ruble, rupee, shekel, shilling, sol,
   sou, stiver, won, yen



Bouvier's Law Dictionary, Revised 6th Ed (1856):

FRANC, com. law. The name of a French coin. Five franc pieces, when not of
less fineness than ten ounces and sixteen pennyweights in twelve ounces troy
weight of standard silver, and weighing not less than three hundred and
eighty-four grains each, are made a legal tender, at the rate of ninety-
three cents each. Act of June 25, 1834, s. 1, 4 Sharsw. Cont. of Story's L.
U. S. 2373.
     2. In all computations at the custom house, the franc of France and of
Belgium shall be estimated at eighteen cents six. mills. Act of May 22,
1846. See Foreign coins.