gm (gram): The abbreviation gm stands for gram, a unit of measurement of weight and mass in the metric system. In weight, a gram is equal to a thousandth of a kilogram. In mass, a gram is equal to a thousandth of a liter (one cubic centimeter) of water at 4 degrees centigrade.
The word "gram" comes from the Late Latin "gramma" meaning a small weight via the French "gramme." The symbol for gram is g.