absorptance

noun Physics, Optics.

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

noun

1. 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