## candela, $$\text{cd}$$

https://doi.org/10.1351/goldbook.C00787
The candela, symbol $$\text{cd}$$, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 x 10E12 Hz, Kcd, to be 683 when expressed in the unit lm W-1, which is equal to cd sr W-1, or cd sr kg-1 m-2 s3, where the kilogram, metre and second are defined in terms of h, c and ΔνCs.
Source:
BIPM, The International System of Units, SI Brochure, 9th ed. (2019) (http://www.bipm.org/en/publications/si-brochure/)