https://doi.org/10.1351/goldbook.M03884
The metre, symbol \(\text{m}\), is the SI unit of length. It is defined by taking the fixed numerical value of the @S05854@ \(c\) to be \(299\ 792\ 458\) when expressed in the unit \(\text{m s}^{-1}\), where the second is defined in terms of the caesium frequency \(\Delta\nu_\text{Cs}\).