The SI unit of luminous intensity.
It is the luminous intensity, in the perpendicular direction, of a surface of 1/600.000 square metre of a black body at the temperature of freezing platinum, under a pressure of 101 325 newtons per square metre.
Definition adopted by the 13th General Conference on Weights and Measures (1967).
Symbol: cd 1 cd = 1 lumen per steradian (lm/sr)
Note: Candle, English Candle, Decimal Candle, Hefner Candel, Carcel-other units of luminous intensity now superseded by the candela. It is recommended that these terms should not in future be used. For reference, these units (other than the carcel) are approximately the same as the candela (within +/- 20%).
A carcel is approximately 10 candelas.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
International System of Units
steradian (square radian)
Celsius (previously Centigrade)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM