The Collaborative International Dictionary of English v.0.48:

Fisc \Fisc\ (f[i^]sk), n. [F. fisc, fr. L. fiscus basket, money
   basket, treasury; prob. akin to fascis bundle. See Fasces.]
   A public or state treasury. --Burke.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fisc
    n 1: a state treasury or exchequer or a royal treasury;
         originally the public treasury of Rome or the emperor's
         private purse

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

FISC, civil law. The treasury of a prince. The public treasury. Hence to
confiscate a thing, is to appropriate it to the fisc. Paillet, Droit Public,
21, n, says that fiscus, in the Roman law, signified the treasure of the
prince, and aerarium, the treasure of the state. But this distinction was
not observed in France. See Law 10, ff. De jure Fisci.