The strip of ground marking the formal, religiously constituted boundary of a Roman city.
The pomerium is usually taken to denote the open space running inside and outside the walls of a city, which was consecrated by the pontifex and ordained to be left free from buildings.
Late 16th century; earliest use found in Richard Grenewey (fl. 1598), translator. From classical Latin pōmoerium, pōmērium strip of ground marking the formal, religiously constituted boundary of a Latin or Etruscan town, boundary of any town, limits of a topic or subject, usually derived (as by ancient etymologists) from post behind + moerus, mūrus wall + -ium, neuter of -ius, suffix forming adjectives, but perhaps of Etruscan origin, the rites used for founding a city being Etruscan.