Greenwich Mean Time
Concise Oxford English Dictionary © 2008 Oxford University Press:
Greenwich Mean Time /ˈgrɛnɪtʃ, ˈgrɪnɪdʒ/
▶noun the mean solar time at the Greenwich meridian, adopted as the standard time in a zone that includes the British Isles.
– origin Greenwich in London, former site of the Royal Observatory.
'Greenwich Mean Time' also found in these Oxford entries:

