The ratio of absorbed to incident radiation.
(optics, physics) Absorbed radiation and incident radiation in a ratio format; a measurement that shows how well a surface absorbs radiation. [First attested in the mid 20th century.]
Origin of absorptance
- absorpt(ion) –ance
From American Heritage Dictionary of the English Language, 5th Edition
- Circa 20th century, from absorption +"Ž -ance.