https://doi.org/10.1351/goldbook.S05854
The speed of light in vacuum, c, is one of seven fixed constants defining the International System of Units, the SI, with c=299 792 458 m s1. The speed of light is considered as a fundamental constant of nature.
Source:
BIPM, The International System of Units, SI Brochure, 9th ed. (2019), p. 127ff [Terms] [Book]