one of the Six Counties of Northern Ireland, formerly an administrative area.
the chief town of Londonderry, a city and port on the River Foyle near its outlet on the north coast; population 89,900 (est. 2009). It was formerly called Derry, a name still used by many. In 1613 it was granted to the City of London for colonization and became known as Londonderry.
Londonderry in other Oxford dictionaries
Definition of Londonderry in the US English dictionary