Limes

A limes ( /ˈlaɪmiːz/) was a border defense or delimiting system of Ancient Rome. It marked the boundaries of the Roman Empire.

The Latin noun limes had a number of different meanings: a path or balk delimiting fields, a boundary line or marker, any road or path, any channel, such as a stream channel, or any distinction or difference. In Latin, the plural form of limes is limites.

The word limes, hence, was utilized by Latin writers to denote a marked or fortified frontier. This latter sense has been adapted and extended by modern historians concerned with the frontiers of the Roman Empire; e.g., Hadrian's wall in the north of England is sometimes styled the Limes Britannicus, the frontier of the Roman province of Arabia facing the desert is called the Limes Arabicus, and so forth.

This was the traditional definition and usage of the term. It is now more common to accept that limes was not a term used by the Romans for the imperial frontier, fortified or not. This is a modern, anachronistic interpretation. The term became common after the third century, when it denoted a military district under the command of a dux limitis