kel·​vin | \ ˈkel-vən How to pronounce kelvin (audio) \

Definition of kelvin

 (Entry 1 of 3)

: the base unit of temperature in the International System of Units that is equal to 1/273.16 of the Kelvin scale temperature of the triple point of water



Definition of Kelvin (Entry 2 of 3)

: relating to, conforming to, or having a thermometric scale on which the unit of measurement equals the Celsius degree and according to which absolute zero is 0 K, the equivalent of −273.15°C


biographical name
Kel·​vin | \ ˈkel-vən How to pronounce Kelvin (audio) \

Definition of Kelvin (Entry 3 of 3)

1st Baron 1824–1907 William Thomson British mathematician and physicist

Examples of kelvin in a Sentence


a temperature of 200 degrees Kelvin

Recent Examples on the Web: Noun

Four out of the seven base units within the SI will be changed in total, including the ampre, the kelvin, and the mole. David Grossman, Popular Mechanics, "Why the World's Measuring Systems Just Changed—and What It Means," 20 May 2019 Color temperatures range from about 1,400 to 10,000 kelvin. New York Times, "These Lights Are Like a Mood Ring for Your Room," 8 May 2018 So on the kelvin scale, the processor is 180 times colder than the temperature of space. Scientific American, "Readers Respond to the December 2017 Issue," 1 Dec. 2017 The review concerns a potential redefinition of the ampere (a unit of electricity), the kelvin (temperature), the mole (measurement of atoms and or molecules) and the kilogram. David Grossman, Popular Mechanics, "These Basic Units of Measurement Could Change in 2018," 20 Oct. 2017 Cornell and Wieman were trying to cool a puff of rubidium gas to within a few billionths of a degree of absolute zero—colder than any place in nature, even the 2.73 kelvins of space. Adrian Cho, Science | AAAS, "Coolest science ever headed to the space station," 7 Sep. 2017 It isn’t measured by degrees, but individual kelvins. Bill Andrews, Discover Magazine, "The Names Behind the Units of Measure," 10 Apr. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'kelvin.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of kelvin


1968, in the meaning defined above


1908, in the meaning defined above

History and Etymology for kelvin


William Thomson, Lord Kelvin

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Dictionary Entries near kelvin






Kelvin's law

Kelvin balance

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5 Jun 2019

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The first known use of kelvin was in 1908

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English Language Learners Definition of Kelvin

technical : relating to or having a scale for measuring temperature on which the boiling point of water is at 373.1 degrees above zero and the freezing point is at 273.15 degrees above zero


kel·​vin | \ ˈkel-vən How to pronounce kelvin (audio) \

Medical Definition of kelvin

 (Entry 1 of 2)

: the base unit of temperature in the International System of Units that is equal to 1/273.16 of the Kelvin scale temperature of the triple point of water and also to the Celsius degree



Medical Definition of Kelvin (Entry 2 of 2)

: relating to, conforming to, or being the Kelvin scale

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to move with exaggerated bouncy motions

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