# absorptivity

CEFR C1 · Noun

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

## Definition

the ability of a material to take in and hold onto energy, like heat or light. It measures how much of that energy a surface can absorb rather than reflect.

For teachers: the capacity of a material to absorb electromagnetic radiation, such as light or heat, without reflecting it. Often expressed as a dimensionless coefficient or percentage.

## Examples

- The black paint has a high absorptivity for sunlight.
- Engineers selected a material with high thermal absorptivity to ensure the solar panels captured as much heat as possible.
- In the study of climate change, scientists calculate the Earth's overall absorptivity to determine how much solar radiation is retained by the atmosphere versus reflected back into space.

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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.