Greenwich Mean Time
- The local time at the 0° meridian, which passes through Greenwich, England. Greenwich mean Time has been succeeded by Coordinated Universal Time as the basis for the worldwide system of time. Its abbreviation is GMT. Formerly called Greenwich Civil Time.
- noun the exact solar time on the prime meridian (at 0º latitude, found in Greenwich, UK) from which the local time in all time zones is calculated.
- noun the local time on the 0° meridian where it passes through Greenwich, England, used to calculate international time zones