The district occupied entirely by the city of Washington; chosen by George Washington as the site of the capital of the United States and created out of land ceded by Maryland and Virginia WordNet 3.0 & Open English WordNet

The federal capital region of the United States of America. The City of Washington used to be a municipality within the District of Columbia until 1871, when two entities were merged. For this reason, the district is also generally known as Washington, D.C. Wiktionary

Federal capital of the United States of America. Wiktionary (translation)