The metre (or meter; US spelling) is the SI base unit of length and uses the symbol m.
Originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole but was redefined in 1799 in terms of a prototyped metre bar (this bar was changed again in 1889).
In 1983 the current definition was adopted and it is now the most common unit in any property in the world and is used in thousands of formulae to describe countless characteristics.
Let's hear it for the metre!
The league is a ancient unit of length that doesn't below to a unit system. Its symbol is simply - league.
It was originally an ancient Celtic unit as well as being common in Latin America and meant the distance "a person could walk in an hour". It is no longer a recognised unit in any nation.
Once it started to be quantified, in Argentina (legua) it represented 5.572 km, in England it was quantified as 3 miles and at sea a league is 3 nautical miles (3.452 miles).