# absorptance

CEFR C1 · Noun

Source: https://englishreference.com/word/absorptance
Updated: 2026-05-18

## Definition

the ability of a material to absorb light or heat. It measures how much of the energy is taken in rather than reflected or transmitted.

For teachers: the fraction of incident electromagnetic radiation or thermal energy that is absorbed by a surface or medium. Often expressed as a dimensionless quantity between 0 and 1.

## Examples

- The black paint has a high absorptance of sunlight.
- Engineers calculated the absorptance of the solar panels to determine how much energy they could capture during the winter months.
- In thermal imaging, the absorptance of a material determines how effectively it converts incoming infrared radiation into heat, which is critical for the accuracy of the final temperature readings.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.