[ ab-sawrp-tuh ns, -zawrp- ]
/ æbˈsɔrp təns, -ˈzɔrp- /

noun Physics, Optics.

the ratio of the amount of radiation absorbed by a surface to the amount of radiation incident upon it.

Origin of absorptance

1930–35; translation of German Absorptionsvermögen. See absorption, -ance
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British Dictionary definitions for absorptance


absorption factor

/ (əbˈsɔːptəns, -ˈzɔːp-) /


physics a measure of the ability of an object to absorb radiation, equal to the ratio of the absorbed radiant flux to the incident flux. For a layer of material the ratio of the flux absorbed between the entry and exit surfaces of the layer to the flux leaving the entry surface is the internal absorptanceSymbol: α Compare reflectance, transmittance

Word Origin for absorptance

C20: absorption + -ance
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012