\begin{definition}[Definition:Metric System/Length/Metre]
The '''meter''' (UK English: '''metre''') is the SI base unit of length.
It was initially invented as <math>10^{-7}</math> the distance from the Earth's equator to the North Pole (at sea level).
Since 1983, it is defined as the distance travelled by light in vacuum in <math>\frac 1 {299 \, 792 \, 458}</math> of a second.
\end{definition}