Kelvin

American  

[kel-vin] / ˈkɛl vɪn /

noun

1. William Thomson, 1st Baron, 1824–1907, English physicist and mathematician.

2. (lowercase) the basic unit of temperature in the International System of Units (SI), formally defined to be approximately 1/273 of the triple point of water. K

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adjective

1. Thermodynamics. noting or pertaining to an absolute scale of temperature Kelvin scale in which the degree intervals are equal to those of the Celsius scale and in which absolute zero is 0 degrees Kelvin and the triple point of water has the value of approximately 273 degrees Kelvin.

2. Also Kelwin a male given name.

Kelvin ¹ British  

/ ˈkɛlvɪn /

noun

1. William Thomson, 1st Baron Kelvin. 1824–1907, British physicist, noted for his work in thermodynamics, inventing the Kelvin scale, and in electricity, pioneering undersea telegraphy

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kelvin ² British  

/ ˈkɛlvɪn /

noun

1.  K.  the basic SI unit of thermodynamic temperature; the fraction 1/ 273.16 of the thermodynamic temperature of the triple point of water

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kelvin ¹ Scientific  

/ kĕl′vĭn /

1. The SI unit used to measure temperature, the basic unit of the Kelvin scale. A difference of one degree Kelvin corresponds to the same temperature difference as a difference of one degree Celsius.

2. See Table at measurement See also absolute zero

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Kelvin ² Scientific  

1. British mathematician and physicist known especially for his work on heat and electricity. In 1848 he proposed a scale of temperature independent of any physical substance, which became known as the Kelvin scale.

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Explanation

A kelvin is a unit for measuring temperature. The kelvin scale is based on absolute zero, the coldest possible measurement, so there is no such thing as a negative temperature in kelvins. The Celsius scale is based on kelvins, but the two scales differ in that kelvins measure an absolute temperature, based on a zero that can literally not get any colder. While temperature isn't commonly measured in kelvins outside the science lab, it's a vital way of calculating temperature for scientists. The kelvin is named after the Irish-Scottish physicist Sir William Thompson, also known as Lord Kelvin.

Example Sentences

I’m Kelvin Washington, alongside the usuals, Yvonne Villarreal, we got Mark Olsen as well.

From Los Angeles Times • Feb. 19, 2026

In an interview, Kelvin Coleman, who was head of FAA’s commercial space office during the launches, said his office determined that the risk from the mishaps “was within the acceptable limits of our regulations.”

From Salon • Jan. 12, 2026

A team from the University of Glasgow team worked with volunteers and students to excavate the former Kelvin Wheelies park in Kelvingrove Park.

From BBC • Dec. 30, 2025

In 1867, Lord Kelvin pictured atoms as tiny knots in an invisible medium called the ether.

From Science Daily • Dec. 7, 2025

Other scientists besides Kelvin turned their minds to the problem and came up with results that only deepened the uncertainty.

From "A Short History of Nearly Everything" by Bill Bryson