Dominant Wavelength (of a colour stimulus, not purple)
The wavelength of the monochromatic light stimulus that, when combined in suitable proportions with the specified achromatic light stimulus, yields a match with the colour stimulus considered.
Note 1: When the dominant wavelength cannot be given (this applies to purples) its place is taken by the complementary wavelength.
Note 2: For the definitions of Achromatic and Specified Achromatic Light Stimulus, see Reference: C.I.E. In particular, for surface colours, the light source serving as illuminant is taken as achromatic.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
Celsius (previously Centigrade)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM