(Term of photometry)
Colors that have the same visual appearance (= the same "tristimulus values"), but different spectral composition, are called metameric. The light color emitted by different types of light sources with the same color temperature will usually be metameric, but they may still be distinguishable by looking at their color rendering index. With monochromatic sources, the color temperature directly relates to a corresponding wavelength
Metameric colors will share the same location on the CIE chromaticity diagram.
(The term metamer is also used in other contexts, eg. in chemistry).
color rendering index