[ab-sawrp-tuh ns, -zawrp-]
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
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
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