chief city and capital of England, Latin Londinium (c.115), according to the "Cambridge Dictionary of English Place-Names," "unexplained." It is often said to be "place belonging to a man named *Londinos," a supposed Celtic personal name meaning "the wild one," "but this etymology is rejected in an emphatic footnote in Jackson 1953 (p.308), and we have as yet nothing to put in its place" [Margaret Gelling, "Signposts to the Past: Place-Names and the History of England," Chichester, 1978]. Its mythical history is told in Layamon's "Brut" (c. 1200).
In late Old English often with -burg, -wic, or -ceaster. As an adjective, Old English had Lundenisc, but this seems to have fallen from use, and modern Londonish (1838) probably is a re-coinage. Also Londony (1884); Londonesque (1852); Londinensian (George Meredith); Londonian (1824, marked "rare" in OED).
London Bridge the children's singing game is attested from 1827. London broil "large flank steak broiled then cut in thin slices" attested 1930s, American English; London fog first attested 1785.