Capacity

Capacity is the main characteristic of thermal radiation that is sent from the surface of a heated body.

Ability is calculated per unit body angle; it (ε) in all directions (also called luminosity) at according to Lambert's law is determined by the ratio ε = πВ. Spectral capacity is calculated per unit frequency interval (or wavelength). It is related to the absorptive capacity of the body by Kirchhoff's law of radiation, for a completely black body it is determined by Planck's law of radiation.

Sources:

Словник Webster's Dictionary https://www.merriam-webster.com/

Science News For Students https://www.sciencenewsforstudents.org/article/