Origin: Latin suffix -ance
Absorptance has 2 different meanings across 1 category:
a measure of the rate of decrease in the intensity of electromagnetic radiation (as light) as it passes through a given substance; the fraction of incident radiant energy absorbed per unit mass or thickness of an absorber
"absorptance equals 1 minus transmittance"
Absorbed radiation and incident radiation in a ratio format; a measurement that shows how well a surface absorbs radiation.