Alternative term: Black Body, Planckian Radiator
The thermal radiator which absorbs completely all incident radiation, whatever the wavelength, the direction of incidence or the polarisation. This radiator has, for any wavelength, the maximum spectral concentration of radiant exitance at a given temperature.
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