from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun The base unit of mass in the International System, equal to 1,000 grams (2.2046 pounds).
  • noun Kilogram force.

from The Century Dictionary.

  • noun The ultimate standard of mass in the French system of weights and measures, equal to 1,000 grams; the mass of a certain cylinder of platinum deposited in the Archives of France on the 22d of June, 1799, and thence known as the Kilogramme des Archives.

from the GNU version of the Collaborative International Dictionary of English.

  • noun A measure of weight, being a thousand grams, equal to 2.2046226 pounds avoirdupois (15,432.34 grains). It is equal to the weight of a cubic decimeter of distilled water at the temperature of maximum density, or 39° Fahrenheit.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun In the International System of Units, the base unit of mass; the mass of a specific cylinder of platinum-iridium alloy kept at the International Bureau of Weights and Measures in France. Symbol: kg
  • noun proscribed Hence, the unit of weight such that one-kilogram mass is also a one-kilogram weight.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun one thousand grams; the basic unit of mass adopted under the Systeme International d'Unites


from Wiktionary, Creative Commons Attribution/Share-Alike License

From French kilogramme, composed of kilo- + gramme.


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  • The only SI unit still maintained by a physical artifact: a platinum-iridium bar kept in the International Bureau of Weights and Measures at Sevres, France.

    February 5, 2010

  • from

    "The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed

    numerical value of the Planck constant h to be 6.626 070 15 × 10–34 when expressed

    in the unit J s, which is equal to kg m2 s


    , where the metre and the second are

    defined in terms of c and ∆νCs."

    Nov 2018 redefinition of kilogram.

    Mandatory XKCD comic:

    November 17, 2018