The Collaborative International Dictionary of English v.0.48:

Congiary \Con"gi*a*ry\, n.; pl. Congiaries. [L. congiarium,
   fr. congius a liquid measure.]
   A present, as of corn, wine, or oil, made by a Roman emperor
   to the soldiers or the people; -- so called because measured
   to each in a congius. --Addison.
   [1913 Webster]

   Note: In later years, when gifts of money were distributed,
         the name congius was retained.
         [1913 Webster]