kilogram

noun

ki·​lo·​gram ˈki-lə-ˌgram  ˈkē-lə- 

1

: the base unit of mass in the International System of Units that is defined by setting the fixed numerical value of Planck's constant to 6.62607015 x 10^–34 joule seconds see Metric System Table

2

: a unit of force or weight equal to the weight of a kilogram mass under a gravitational attraction equal to that of the earth

Did you know?

The original concept of the kilogram, as the mass of a cubic decimeter of water (a bit more than a quart), was adopted as the base unit of mass by the new revolutionary government of France in 1793. In 1875, in the Treaty of the Meter, 17 countries, including the U.S., adopted the French kilogram as an international standard. In 1889 a new international standard for the kilogram, a metal bar made of platinum iridium, was agreed to; President Benjamin Harrison officially received the 1-kilogram cylinder for the U.S. in 1890. But no one uses that bar very often; for all practical purposes, a kilogram equals 2.2 pounds.

Examples of kilogram in a Sentence

Recent Examples on the Web

The $7 monthly subsidy will be enough to cover 100 eggs, a kilogram of red meat, or a few kilograms of rice or chicken at current prices in Iran, the New York Times reported. —Brady Knox, The Washington Examiner, 8 Jan. 2026

Standing 165 centimeters tall and weighing 71 kilograms, the GR-3 offers 55 degrees of freedom and is equipped with tactile sensors distributed across its body for responsive interaction. —Kaif Shaikh, Interesting Engineering, 8 Jan. 2026

The prized fish, which was caught off Oma in northern Aomori prefecture, weighed in at a hefty 536 pounds (243 kilograms). —Rachel Cormack, Robb Report, 5 Jan. 2026

The mission is designed to be a technology demonstration of the Blue Moon Mark 1 cargo lander design, including precision landing systems and propulsion tech that will support later commercial and NASA payload deliveries to the lunar surface, with a capacity of up to 6,600 pounds (3,000 kilograms). —Andrew Jones, Space.com, 5 Jan. 2026

Word History

Etymology

French kilogramme, from kilo- + gramme gram

First Known Use

1797, in the meaning defined at sense 1

Phrases Containing kilogram

• kilogram-meter
• meter-kilogram-second

Rhymes for kilogram

• abraham
• anagram
• cablegram
• cofferdam
• dendrogram
• diagram
• diaphragm
• epigram
• hexagram
• histogram
• hologram
• instagram

Kids Definition

kilogram

noun

ki·​lo·​gram ˈkē-lə-ˌgram  ˈkil-ə- 

1

: the basic unit of mass in the metric system that has been accepted by international agreement and is nearly equal to the mass of 1000 cubic centimeters of water at its highest density see metric system

2

: the weight of a kilogram mass on the earth

he weighs 80 kilograms

see metric system

Medical Definition

kilogram

noun

ki·​lo·​gram

variants or chiefly British kilogramme

ˈkil-ə-ˌgram  ˈkē-lə- 

1

: the base unit of mass in the International System of Units that is equal to the mass of a prototype agreed upon by international convention and that is nearly equal to the mass of 1000 cubic centimeters of water at the temperature of its maximum density

2

: a unit of force equal to the weight of a kilogram mass under a gravitational attraction equal to that of the earth