kelvin

Pluralkelvins

1. 1
   nouncountable

   The base unit of thermodynamic temperature in the International System of Units, equal to very nearly 1/273.16 of the thermodynamic temperature of the triple point of water.

   Liquid nitrogen boils at about 77 kelvins.

   The sensor must be cooled to below one kelvin before it can pick up the faint signal.

   Note

   The unit takes its name from William Thomson, the Irish-born Scottish physicist who became Lord Kelvin. Even so, it is written in lowercase like any common noun and takes an ordinary plural: ice melts above 273.15 kelvins. You may also meet degree Kelvin or degree absolute, but the plain noun needs no "degree" in front of it.

2. 2
   noununcountable

   A measure of how warm or cool a color of light is, given as the temperature at which a glowing blackbody would give off that color.

   Photographers set the camera's white balance to match the kelvin of the studio lamps.

   Many LED bulbs print their kelvin on the box, from warm white to cool daylight.

3. 3
   nouncountable

   A difference of one degree on the kelvin scale, used as a unit for measuring temperature intervals.

   The reactor's coolant warmed by only two kelvins during the test.

   Overnight, the sample's temperature drifted by less than a kelvin.

   Note

   One word does two jobs on this scale: it names a temperature and a step between temperatures. The gap between water's freezing and boiling points is 100 kelvins, though neither point is anywhere near 100 kelvins as a temperature reading; ice melts above 273.15. The preposition usually tells them apart: "at 300 kelvins" is a temperature, "by two kelvins" or "a rise of one kelvin" is a step.

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