Radiantness vs. Radiance — What's the Difference?

(rare) radiance

In radiometry, radiance is the radiant flux emitted, reflected, transmitted or received by a given surface, per unit solid angle per unit projected area. Spectral radiance is the radiance of a surface per unit frequency or wavelength, depending on whether the spectrum is taken as a function of frequency or of wavelength.

The quality or state of being radiant.

(Physics) The radiant energy emitted per unit time in a specified direction by a unit area of an emitting surface.

The quality of being radiant, shining, bright or splendid.

(physics) The flux of radiation emitted per unit solid angle in a given direction by a unit area of a source.

The quality of being radiant; brilliancy; effulgence; vivid brightness; as, the radiance of the sun.

The amount of electromagnetic radiation leaving or arriving at a point on a surface

The quality of being bright and sending out rays of light

An attractive combination of good health and happiness;