What is London?

London definition and meaning on Dictionary terms:
Jack,1876a??1916, U.S. short-story writer and novelist.
a metropolis in SE England, on the Thames: capital of the United Kingdom.
City of, an old city in the central part of the former county of London: the ancient nucleus of the modern metropolis. 1 sq. mi. (3 sq. km).
County of, a former administrative county comprising the City of London and 28 metropolitan boroughs, now part of Greater London.
Greater. Also Greater London Council. an urban area comprising the city of London and 32 metropolitan boroughs. 609 sq. mi. (1575 sq. km).
a city in S Ontario, in SE Canada.