Greenwich Time

noun
1.
the time as measured on the prime meridian running through Greenwich, England: used in England and as a standard of calculation elsewhere.
Also called Greenwich Mean Time, Greenwich Civil Time, universal time, Universal Time.
Origin
1840-50
British Dictionary definitions for Greenwich Time

Greenwich Mean Time

noun
1.
mean solar time on the 0° meridian passing through Greenwich, England, measured from midnight: formerly a standard time in Britain and a basis for calculating times throughout most of the world, it has been replaced by an atomic timescale GMT See universal time
Usage note
The name Greenwich mean time is ambiguous, having been measured from mean midday in astronomy up to 1925, and is not used for scientific purposes. It is generally and incorrectly used in the sense of universal coordinated time, an atomic timescale available since 1972 from broadcast signals, in addition to the earliest sense of universal time, adopted internationally in 1928 as the name for GMT measured from midnight