A pentapolis, from the Greek words penta 'five' and polis 'city(-state)' is geographic and/or institutional grouping of five cities.
Significant historical cases
in the biblical Holy Land, the word, occurring in Wisdom, x, 6, designates the region where five cities — Sodom, Gomorrha, Segor (A. V., Zoar), Admah and Zeboim — united to resist the invasion of Chedorlaomer (Genesis, xiv), and of which four were shortly after utterly destroyed.
The Western Pentapolis: five main Greek colonies that came to be in the Roman province of Libya Superior, the western part of Cyrenaica until Diocletian's Tetrarchy reform in AD 296 (now Libya). The most important was Cyrene and its port Apollonia, Ptolemais (the next capital after Cyrene's destruction by an earthquake), Barca (the later Arab provincial capital Barka) and Berenice (modern Benghazi); also known as the Pentapolis inferior ('lower P.'). This is the Pentapolis that is referenced in the official title of the Eastern Orthodox Patriarch of Alexandria and the Pope of the Coptic Orthodox Church.