<p><strong>Noun</strong></p><ul><li>A unit of mass equal to 1,000 grams; the basic unit of mass in the International System of Units (SI).</li><li>Up until 2019, the kilogram was defined as equal to the mass of an international prototype, a platinum-iridium cylinder kept in Sèvres, France.</li><li>The kilogram has since been redefined in terms of universal physical constants, including the speed of light and Planck's constant.</li></ul><p><strong>Abbreviation</strong></p><ul><li>kg: a unit of force and weight, equal to the force that produces an acceleration of 9.80665 meters per second per second when acting on a mass of one kilogram.</li></ul>