A borough is an administrative division in various English-speaking countries. In principle, the term "borough" designates a self-governing walled town, although in practice, official use of the term varies widely. 

The word "borough" derives from common Proto-Germanic "*burgz", meaning "fort": compare with "bury", "burgh" and "brough" (England), "burgh" (Scotland), "Burg" (Germany), "borg" (Scandinavia), "burcht" (Dutch), "boarch" (West Frisian), and the Germanic borrowing present in neighbouring Indo-european languages such as "borgo" (Italian), "bourg" (French), "burgo" (Spanish and Portuguese), "burg" (Romanian), "purg" (Kajkavian) and "durg" (दर्ग) (Hindi) and "arg" (ارگ) (Persian). The incidence of these words as suffixes to place names (for example, Aldeburgh, Bamburgh, Tilbury, Tilburg, Strasbourg (Strossburi in the local dialect), Luxembourg, Edinburgh, Grundisburgh, Hamburg, Gothenburg) usually indicates that they were once fortified settlements. 

In the Middle Ages, boroughs were settlements in England that were granted some self-government; burghs were the Scottish equivalent. In medieval England, boroughs were also entitled to elect members of parliament. The use of the word "borough" probably derives from the burghal system of Alfred the Great. Alfred set up a system of defensive strong points (Burhs); in order to maintain these settlements, he granted them a degree of autonomy. After the Norman Conquest, when certain towns were granted self-governance, the concept of the burh/borough seems to have been reused to mean a self-governing settlement.
Does burgz mean anything else?
The word "borough" derives from common Proto-Germanic "*burgz", meaning "fort":