A unit of mass equal to 1000 grams. It is one of the seven base SI units, and is defined as the mass of the international prototype, made of platinum-iridium, and kept at the BIPM (BIPM 1998, p. 95).
References
Bureau International des Poids et Mesures. "The International System of Units (SI), 7th ed." 1998. http://www1.bipm.org/en/si/si_brochure/.
