The Collaborative International Dictionary of English v.0.48:

Gram \Gram\, Gramme \Gramme\ (gr[a^]m), n. [F. gramme, from Gr.
   gra`mma that which is written, a letter, a small weight, fr.
   gra`fein to write. See Graphic.]
   The unit of mass or weight in the metric system. It was
   intended to be exactly, and is very nearly, equivalent to the
   weight in a vacuum of one cubic centimeter of pure water at
   its maximum density. It is equal to 15.432 grains. See
   Grain, n., 4.
   [1913 Webster]

   Gram degree, or Gramme degree (Physics), a unit of heat,
      being the amount of heat necessary to raise the
      temperature of one gram of pure water one degree
      centigrade.

   Gram equivalent (Electrolysis), that quantity of the metal
      which will replace one gram of hydrogen.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Gramme \Gramme\, n.
   Same as Gram the weight.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gramme
    n 1: a metric unit of weight equal to one thousandth of a
         kilogram [syn: gram, gramme, gm, g]

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

GRAMME. A French weight. The gramme is the weight of a cubic centimetre of
distilled water, at the temperature of zero. It is equal to 15.4441 grains
troy, or 5.6481 drachms avoirdupois. Vide. Measure.