Definition of Merriam-Webster used for technical definition of IEC term "radiance", defined in IEC-IEV already
Use official definition of IEC-IEV:
radiance: brightness (deprecated); the radiant power in a given direction and at a given point of a real or hypothetical surface transmitted by an elementary beam passing through the given point and propagating in the solid angle containing the given direction divided by the product of the value of this solid angle, the area of section of that beam containing the given point and the cosine of the angle between the normal to that section and the direction of the beam
NOTE – The surface may be that of a source or a surface emitting, receiving or intersecting a light beam. Source: MOD 845-01-34
The IEC Electropedia has many different wordings for the same term "irradiance" (not radiance). They all mean the same thing as the definition in 7-420. It is not clear therefore if we should change the definition.