Definition of Field reeve
In old English law, an officer elected by the owners of a regulated pasture to keep in order the fences, ditches, etc., on the land, to regulate the times during which animals are to be admitted to the pasture, and generally to maintain and manage the pasture subject to the instructions of the owners.
That's the definition of Field reeve in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.