emissivity
noun
emis·siv·i·ty
ˌe-mə-ˈsi-və-tē 
ˌē-ˌmi-ˈsi-
plural emissivities
: the relative power of a surface to emit heat by radiation : the ratio of the radiant energy emitted by a surface to that emitted by a blackbody at the same temperature
Examples of emissivity in a Sentence
Recent Examples on the Web
Concrete, for example, is rated at 0.85, brick can range between 0.73 and 0.93 depending on its composition, and bare metals like brass can have emissivity values as low as 0.03.
—
Joan Meiners, USA TODAY, 10 Sep. 2024
This heat exchange depends on the properties of the TPV emitter, such as its emissivity and temperature, the optical properties of the cell, and other experimental conditions.
—IEEE Spectrum, 21 Feb. 2024
So emissivity is essentially the opposite of reflectivity.
—Rhett Allain, WIRED, 25 Aug. 2023
Both reflectivity and emissivity depend on the wavelength of light.
—Rhett Allain, WIRED, 25 Aug. 2023
At the base Premium level, the roof has a special coating called low-e, or low emissivity, to keep the interior cool by blocking some wavelengths of light.
—Kristin Shaw, Popular Science, 13 Mar. 2023
Finally, there is that last symbol—ε this is called the emissivity.
—WIRED, 3 Feb. 2023
An object that's a perfect thermal emitter has an emissivity of 1, and one that doesn't produce any thermal radiation has a value of 0.
—WIRED, 3 Feb. 2023
An elevation model of Idunn Mons on Venus, with thermal emissivity data overlain on the surface.
—Nathaniel Scharping, Discover Magazine, 18 Oct. 2016
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Joan Meiners, USA TODAY, 10 Sep. 2024
This heat exchange depends on the properties of the TPV emitter, such as its emissivity and temperature, the optical properties of the cell, and other experimental conditions.
—IEEE Spectrum, 21 Feb. 2024
So emissivity is essentially the opposite of reflectivity.
—Rhett Allain, WIRED, 25 Aug. 2023
Both reflectivity and emissivity depend on the wavelength of light.
—Rhett Allain, WIRED, 25 Aug. 2023
At the base Premium level, the roof has a special coating called low-e, or low emissivity, to keep the interior cool by blocking some wavelengths of light.
—Kristin Shaw, Popular Science, 13 Mar. 2023
Finally, there is that last symbol—ε this is called the emissivity.
—WIRED, 3 Feb. 2023
An object that's a perfect thermal emitter has an emissivity of 1, and one that doesn't produce any thermal radiation has a value of 0.
—WIRED, 3 Feb. 2023
An elevation model of Idunn Mons on Venus, with thermal emissivity data overlain on the surface.
—Nathaniel Scharping, Discover Magazine, 18 Oct. 2016
Cite this Entry
“Emissivity.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/emissivity. Accessed 21 Jul. 2025.
Copy CitationMedical Definition
emissivity
noun
emis·siv·i·ty
ˌem-ə-ˈsiv-ət-ē
ˌē-ˌmis-ˈiv-
ˌē-ˌmis-ˈiv-
plural emissivities
: the relative power of a surface to emit heat by radiation : the ratio of the radiant energy emitted by a surface to that emitted by a blackbody at the same temperature
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