The gram (also gramme in British English), (Greek/Latin root grámma); symbol g, is a unit of mass.
Originally defined as "the absolute weight of a volume of pure water equal to the cube of the hundredth part of a metre, and at the temperature of melting ice" (later 4 °C), a gram is now defined as one one-thousandths of the SI base unit, the kilogram, or 1×10-3 kg, which itself is defined as being equal to the mass of a physical prototype preserved by the International Bureau of Weights and Measures.