a borough of Greater London on the Thames; zero degrees of longitude runs through Greenwich; time is measured relative to Greenwich Mean Time
"The historic observatory in Greenwich, where the prime meridian passes and GMT was once calculated, now serves as a key part of the London Borough."
A town in east London, on the south bank of the River Thames in Greater London, England, through which the prime meridian passes.
"Greenwich is a historic town in east London where the prime meridian runs along its famous Royal Observatory."
The name Greenwich comes from Old English and literally means "green harbor" or "green settlement." It entered English usage as a place name for the area near London.