Definition:Imperial/Area/Acre/Historical Note

Historical Note on Acre
The acre is a traditional measure of land arising from the days of ploughing in mediaeval times and earlier.

It was defined as the area of land that could be ploughed by $1$ ploughman with $1$ ox in $1$ day.

It is noted that an acre is not actually defined as a square area, but as an oblong strip $10$ times as long as it is wide.

The reason is readily apparent: its length is, as is apparent from its definition, one furlong, that is, furrow-long.